U.S. patent application number 15/550326 was filed with the patent office on 2018-01-25 for method and apparatus for calibration of an antenna.
This patent application is currently assigned to China Academy of Telecommunications Technology. The applicant listed for this patent is China Academy of Telecommunications Technology. Invention is credited to Chuanjun LI, Xin SU.
Application Number | 20180026766 15/550326 |
Document ID | / |
Family ID | 56615292 |
Filed Date | 2018-01-25 |
United States Patent
Application |
20180026766 |
Kind Code |
A1 |
LI; Chuanjun ; et
al. |
January 25, 2018 |
METHOD AND APPARATUS FOR CALIBRATION OF AN ANTENNA
Abstract
An antenna calibration method and apparatus, which are used for
improving calibration accuracy. In the embodiments of the present
invention, sending direction radio frequency channels in an antenna
array are grouped into M groups, an intra-group sending calibration
pilot frequency sequence of each group of sending direction radio
frequency channel is sent at different sending time slots in a time
division manner, and along with the decreasing of the quantity of
each group of sending direction radio frequency channels, a length
of the intra-group sending calibration pilot frequency sequence
mapped on each radio frequency channel used for channel estimation
is increased, thereby improving the accuracy of an inter-channel
compensation factor of each determined sending direction radio
frequency channel.
Inventors: |
LI; Chuanjun; (Beijing,
CN) ; SU; Xin; (Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
China Academy of Telecommunications Technology |
Beijing |
|
CN |
|
|
Assignee: |
China Academy of Telecommunications
Technology
Beijing
CN
|
Family ID: |
56615292 |
Appl. No.: |
15/550326 |
Filed: |
January 8, 2016 |
PCT Filed: |
January 8, 2016 |
PCT NO: |
PCT/CN2016/070497 |
371 Date: |
August 10, 2017 |
Current U.S.
Class: |
370/330 |
Current CPC
Class: |
H04L 5/0048 20130101;
H04B 17/12 20150115; H04L 25/0204 20130101; H04B 17/11 20150115;
H04L 25/0228 20130101; H04L 5/0023 20130101 |
International
Class: |
H04L 5/00 20060101
H04L005/00; H04L 25/02 20060101 H04L025/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 11, 2015 |
CN |
201510073800.0 |
Claims
1. A method for calibrating an antenna, the method comprising the
operations of: obtaining information about grouping of transmitting
radio frequency channels, wherein the transmitting radio frequency
channels in an array of antennas are grouped into M groups, and M
is an integer more than 1; transmitting intra-group transmission
calibration pilot sequences corresponding respectively to the
respective groups of transmitting radio frequency channels over the
corresponding groups of transmitting radio frequency channels
respectively in transmission timeslots of the intra-group
transmission calibration pilot sequences, and performing channel
estimation on the respective groups of transmitting radio frequency
channels according to feedback signals of the intra-group
transmission calibration pilot sequences received over a
calibration receiving channel to obtain channel information of the
M groups of transmitting radio frequency channels, wherein there
are different transmission timeslots of intra-group transmission
calibration pilot sequences corresponding to different groups; and
determining inter-channel compensation coefficients of the
respective transmitting radio frequency channels according to the
channel information of the M groups of transmitting radio frequency
channels.
2. The method according to claim 1, wherein each group of
transmitting radio frequency channels comprises N transmitting
radio frequency channels, wherein: N is 1; or N is an integer more
than 1, and intra-group transmission calibration pilot sequences
are transmitted over different frequency resources in respective
transmitting radio frequency channels in a group.
3. The method according to claim 1, wherein the determining the
inter-channel compensation coefficients of the respective
transmitting radio frequency channels according to the channel
information of the M groups of transmitting radio frequency
channels comprises: selecting a reference channel from each group
of transmitting radio frequency channels respectively according to
the channel information of each group of transmitting radio
frequency channels to obtain M reference channels; transmitting
inter-group transmission calibration pilot sequences over the M
reference channels, and performing channel estimation on the M
reference channels according to feedback signals of the inter-group
transmission calibration pilot sequences received over the
calibration receiving channel to obtain channel information of the
M reference channels; revising the channel information of the group
of transmitting radio frequency channels corresponding to each
reference channel respectively according to the channel information
of each reference channel; and determining the inter-channel
compensation coefficient of each transmitting radio frequency
channel according to the revised channel information of each group
of transmitting radio frequency channels.
4. The method according to claim 3, wherein the selecting a
reference channel from each group of transmitting radio frequency
channels respectively according to the channel information of each
group of transmitting radio frequency channels comprises: for each
group of transmitting radio frequency channels, determining receive
power of each transmitting radio frequency channel in the group of
transmitting radio frequency channels; and determining transmitting
radio frequency channels with their receive power being not below a
first threshold as active transmitting radio frequency channels,
and selecting a reference channel from all the active transmitting
radio frequency channels in the group of transmitting radio
frequency channels according to the receive power of all the active
transmitting radio frequency channels in the group of transmitting
radio frequency channels.
5. The method according to claim 3, wherein the transmitting the
inter-group transmission calibration pilot sequences over the M
reference channels comprises: mapping the inter-group transmission
calibration pilot sequences onto the sub-carriers in the entire
operating bandwidth of each reference channel, wherein the spacing
between sub-carriers to which each reference channel is mapped is a
first sub-carrier offset more than or equal to M, and the spacing
between sub-carriers to which two adjacent reference channels are
mapped is a second sub-carrier offset less than the first
sub-carrier offset; or transmitting the inter-group transmission
calibration pilot sequences over the M reference channels in a
transmission timeslot of the inter-group transmission calibration
pilot sequences in the current calibration period, wherein the
inter-group transmission calibration pilot sequences are
transmitted over different frequency resources of the M reference
channels.
6. (canceled)
7. The method according to claim 3, wherein the performing channel
estimation on the M reference channels according to the feedback
signals of the inter-group transmission calibration pilot sequences
received over the calibration receiving channel comprises:
performing channel estimation on the M reference channels according
to the feedback signals of the inter-group transmission calibration
pilot sequences received over the calibration receiving channel, to
obtain channel information corresponding to the sub-carriers to
which the inter-group transmission calibration pilot sequences are
mapped over each reference channel; and performing interpolation
according to the channel information corresponding to the
sub-carriers to which the inter-group transmission calibration
pilot sequences are mapped over each reference channel, to obtain
channel information corresponding to all the sub-carriers over each
reference channel.
8. The method according to claim 3, wherein the revising the
channel information of the group of transmitting radio frequency
channels corresponding to each reference channel respectively
according to the channel information of each reference channel
comprises: for each group of transmitting radio frequency channels,
calculating a ratio of channel information obtained based upon the
inter-group transmission calibration pilot sequences, to channel
information based upon the intra-group transmission calibration
pilot sequences, of the reference channel of the group of
transmitting radio frequency channels as a revision coefficient
corresponding to the group of transmitting radio frequency
channels; and calculating a product of the revision coefficient
corresponding to the group of transmitting radio frequency
channels, and the channel information of each transmitting radio
frequency channel in the group of transmitting radio frequency
channels obtained based upon the intra-group transmission
calibration pilot sequences as revised channel information of each
transmitting radio frequency channel in the group of transmitting
radio frequency channels.
9. The method according to claim 1, wherein the performing channel
estimation on the respective groups of transmitting radio frequency
channels according to the feedback signals of the intra-group
transmission calibration pilot sequences received over the
calibration receiving channel to obtain the channel information of
the M groups of transmitting radio frequency channels comprises:
performing channel estimation on each group of transmitting radio
frequency channels according to the feedback signals of the
intra-group transmission calibration pilot sequences received over
the calibration receiving channel, to obtain channel information
corresponding to the sub-carriers to which the intra-group
transmission calibration pilot sequences are mapped over each group
of transmitting radio frequency channels; and performing
interpolation according to the channel information corresponding to
the sub-carriers to which the intra-group transmission calibration
pilot sequences are mapped over each group of transmitting radio
frequency channels, to obtain channel information corresponding to
all the sub-carriers over each group of transmitting radio
frequency channels.
10. The method according to claim 1, wherein the transmitting the
intra-group transmission calibration pilot sequences over the
corresponding groups of transmitting radio frequency channels
comprises: mapping the intra-group transmission calibration pilot
sequences corresponding respectively to the respective groups of
transmitting radio frequency channels onto the sub-carriers in the
entire operating bandwidth of the transmitting radio frequency
channels, wherein the spacing between the sub-carriers to which the
respective transmitting radio frequency channels are mapped is a
third sub-carrier offset which is more than or equal to the number
of channels in a group of transmitting radio frequency channels,
and the spacing between sub-carriers to which two adjacent
transmitting radio frequency channels are mapped is a fourth
sub-carrier offset which is less than the third sub-carrier
offset.
11. The method according to claim 1, wherein the transmission
timeslots are guard timeslots; and a first transmission timeslot in
which the intra-group transmission calibration pilot sequences are
transmitted in a first group of transmitting radio frequency
channels, and a second transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in a second group of transmitting radio frequency
channels are two adjacent guard timeslots, or the first
transmission timeslot is spaced from the second transmission
timeslot by X guard timeslots, wherein the first group of
transmitting radio frequency channels, and the second group of
transmitting radio frequency channels are any two groups of
transmitting radio frequency channels with adjacent transmission
timeslots of their intra-group transmission calibration pilot
sequences, and X is an integer more than or equal to 1.
12. An apparatus for calibrating an antenna, the apparatus
comprising a transceiver, a processor, and a memory, wherein the
processor is configured to read and execute program in the memory:
to obtain information about grouping of transmitting radio
frequency channels, wherein the transmitting radio frequency
channels in an array of antennas are grouped into M groups, and M
is an integer more than 1; to transmit intra-group transmission
calibration pilot sequences corresponding respectively to the
respective groups of transmitting radio frequency channels over the
corresponding groups of transmitting radio frequency channels
respectively in transmission timeslots of the intra-group
transmission calibration pilot sequences, and to perform channel
estimation on the respective groups of transmitting radio frequency
channels according to feedback signals of the intra-group
transmission calibration pilot sequences received over a
calibration receiving channel to obtain channel information of the
M groups of transmitting radio frequency channels, wherein there
are different transmission timeslots of intra-group transmission
calibration pilot sequences corresponding to different groups; and
to determine inter-channel compensation coefficients of the
respective transmitting radio frequency channels according to the
channel information of the M groups of transmitting radio frequency
channels.
13. The apparatus according to claim 12, wherein each group of
transmitting radio frequency channels comprises N transmitting
radio frequency channels, wherein: N is 1; or N is an integer more
than 1, and intra-group transmission calibration pilot sequences
are transmitted over different frequency resources in respective
transmitting radio frequency channels in a group.
14. The apparatus according to claim 12, wherein the processor is
configured to select a reference channel from each group of
transmitting radio frequency channels respectively according to the
channel information of each group of transmitting radio frequency
channels to obtain M reference channels; to transmit inter-group
transmission calibration pilot sequences over the M reference
channels, and to perform channel estimation on the M reference
channels according to feedback signals of the inter-group
transmission calibration pilot sequences received over the
calibration receiving channel to obtain channel information of the
M reference channels; and to revise the channel information of the
group of transmitting radio frequency channels corresponding to
each reference channel respectively according to the channel
information of each reference channel; and to determine the
inter-channel compensation coefficient of each transmitting radio
frequency channel according to the revised channel information of
each group of transmitting radio frequency channels.
15. The apparatus according to claim 14, wherein the processor is
further configured: for each group of transmitting radio frequency
channels, to determine receive power of each transmitting radio
frequency channel in the group of transmitting radio frequency
channels; and to determine transmitting radio frequency channels
with their receive power being not below a first threshold as
active transmitting radio frequency channels, and to select a
reference channel from all the active transmitting radio frequency
channels in the group of transmitting radio frequency channels
according to the receive power of all the active transmitting radio
frequency channels in the group of transmitting radio frequency
channels.
16. The apparatus according to claim 14, wherein the processor is
further configured to map the inter-group transmission calibration
pilot sequences onto the sub-carriers in the entire operating
bandwidth of each reference channel, wherein the spacing between
sub-carriers to which each reference channel is mapped is a first
sub-carrier offset more than or equal to M, and the spacing between
sub-carriers to which two adjacent reference channels are mapped is
a second sub-carrier offset less than the first sub-carrier offset
or to transmit the inter-group transmission calibration pilot
sequences over the M reference channels in a transmission timeslot
of the inter-group transmission calibration pilot sequences in the
current calibration period, wherein the inter-group transmission
calibration pilot sequences are transmitted over different
frequency resources of the M reference channels.
17. (canceled)
18. The apparatus according to claim 14, wherein the processor is
further configured: to perform channel estimation on the M
reference channels according to the feedback signals of the
inter-group transmission calibration pilot sequences received over
the calibration receiving channel, to obtain channel information
corresponding to the sub-carriers to which the inter-group
transmission calibration pilot sequences are mapped over each
reference channel; and to perform interpolation according to the
channel information corresponding to the sub-carriers to which the
inter-group transmission calibration pilot sequences are mapped
over each reference channel, to obtain channel information
corresponding to all the sub-carriers over each reference
channel.
19. The apparatus according to claim 14, wherein the processor is
further configured: for each group of transmitting radio frequency
channels, to calculate a ratio of channel information obtained
based upon the inter-group transmission calibration pilot
sequences, to channel information based upon the intra-group
transmission calibration pilot sequences, of the reference channel
of the group of transmitting radio frequency channels as a revision
coefficient corresponding to the group of transmitting radio
frequency channels; and to calculate a product of the revision
coefficient corresponding to the group of transmitting radio
frequency channels, and the channel information of each
transmitting radio frequency channel in the group of transmitting
radio frequency channels obtained based upon the intra-group
transmission calibration pilot sequences as revised channel
information of each transmitting radio frequency channel in the
group of transmitting radio frequency channels.
20. The apparatus according to claim 12, wherein the processor is
further configured: to perform channel estimation on each group of
transmitting radio frequency channels according to the feedback
signals of the intra-group transmission calibration pilot sequences
received over the calibration receiving channel, to obtain channel
information corresponding to the sub-carriers to which the
intra-group transmission calibration pilot sequences are mapped
over each group of transmitting radio frequency channels; and to
perform interpolation according to the channel information
corresponding to the sub-carriers to which the intra-group
transmission calibration pilot sequences are mapped over each group
of transmitting radio frequency channels, to obtain channel
information corresponding to all the sub-carriers over each group
of transmitting radio frequency channels.
21. The apparatus according to claim 12, wherein the processor is
further configured to map the intra-group transmission calibration
pilot sequences corresponding respectively to the respective groups
of transmitting radio frequency channels onto the sub-carriers in
the entire operating bandwidth of the transmitting radio frequency
channels, wherein the spacing between the sub-carriers to which the
respective transmitting radio frequency channels are mapped is a
third sub-carrier offset which is more than or equal to the number
of channels in a group of transmitting radio frequency channels,
and the spacing between sub-carriers to which two adjacent
transmitting radio frequency channels are mapped is a fourth
sub-carrier offset which is less than the third sub-carrier
offset.
22. The apparatus according to claim 12, wherein the transmission
timeslots are guard timeslots; and a first transmission timeslot in
which the intra-group transmission calibration pilot sequences are
transmitted in a first group of transmitting radio frequency
channels, and a second transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in a second group of transmitting radio frequency
channels are two adjacent guard timeslots, or the first
transmission timeslot is spaced from the second transmission
timeslot by X guard timeslots, wherein the first group of
transmitting radio frequency channels, and the second group of
transmitting radio frequency channels are any two groups of
transmitting radio frequency channels with adjacent transmission
timeslots of their intra-group transmission calibration pilot
sequences, and X is an integer more than or equal to 1.
Description
[0001] This application claims the benefit of Chinese Patent
Application No. 201510073800.0, filed with the Chinese Patent
Office on Feb. 11, 2015 and entitled "A method and apparatus for
calibrating an antenna", which is hereby incorporated by reference
in its entirety.
FIELD
[0002] Embodiments of the present invention relate to the field of
communications, and particularly to a method and apparatus for
calibrating an antenna.
BACKGROUND
[0003] The technologies of intelligent antennas have brought
significant advantages to our mobile communication systems, for
example, intelligent antennas can be used with the technologies to
process a baseband digital signal to perform joint detection, and
other operations. Since the characteristics of various elements and
devices, and particularly active devices, used in a system
including the intelligent antennas are very sensitive to their
operating frequencies, ambient temperature, etc., and the
characteristic of each link differently varies due to those
reasons, so the antennas need to be calibrated periodically in a
real network.
[0004] Antenna calibration includes transmission calibration and
reception calibration. Transmission calibration is performed on
radio frequency channels of the antennas in the prior art typically
through Frequency Division Multiplexing (FDM), where transmission
calibration pilot sequences are mapped into the frequency domains
of the respective radio frequency channels. If there is such an
array of antennas that is an array of intelligent antennas at a
large scale, then there will be a smaller number of transmission
calibration pilot sequences mapped onto the respective radio
frequency channels, thus resulting in less precise channel
information of the respective radio frequency channels obtained as
a result of channel estimation using the transmission calibration
pilot sequences mapped onto the respective radio frequency
channels.
[0005] By way of an example, if there is a Long Term Evolution
(LTE) system including radio frequency channels, each of which has
a bandwidth of 20 MHz, and N.sup.sc=1200 sub-carriers, each of
which has a bandwidth of 15 kHz for example, then if there is an
array of intelligent antennas including radio frequency channels of
512 antennas, then frequency-division mapping will be performed by
mapping transmission calibration pilot sequences differently into
the different frequency domains of the respective radio frequency
channels so that the spacing .DELTA.d between every two adjacent
transmission calibration pilot sequences on the respective radio
frequency channels will suffice the total number of radio frequency
channels or more. Accordingly at this time, the number of
transmission calibration pilot sequences which can be mapped onto
the respective radio frequency channels is only
M.sub.sc.sup.AC=.left brkt-bot.1200/512.right brkt-bot.=2, that is,
channel estimation on each radio frequency channel can be performed
using only two transmission calibration pilot sequences in the 20
MHz operating bandwidth of the radio frequency channel.
[0006] In summary, it is highly desirable to provide a method and
apparatus for calibrating an antenna so as to improve the precision
of transmission calibration.
SUMMARY
[0007] Embodiments of the invention provide a method and apparatus
for calibrating an antenna so as to improve the precision of
transmission calibration.
[0008] An embodiment of the invention provides a method for
calibrating an antenna, the method including the steps of: [0009]
obtaining information about grouping of transmitting radio
frequency channels, wherein the transmitting radio frequency
channels in an array of antennas are grouped into M groups, and M
is an integer more than 1; [0010] transmitting intra-group
transmission calibration pilot sequences corresponding respectively
to the respective groups of transmitting radio frequency channels
over the corresponding groups of transmitting radio frequency
channels respectively in transmission timeslots of the intra-group
transmission calibration pilot sequences, and performing channel
estimation on the respective groups of transmitting radio frequency
channels according to feedback signals of the intra-group
transmission calibration pilot sequences received over a
calibration receiving channel to obtain channel information of the
M groups of transmitting radio frequency channels, wherein there
are different transmission timeslots of intra-group transmission
calibration pilot sequences corresponding to different groups; and
[0011] determining inter-channel compensation coefficients of the
respective transmitting radio frequency channels according to the
channel information of the M groups of transmitting radio frequency
channels.
[0012] In an implementation, each group of transmitting radio
frequency channels includes N transmitting radio frequency
channels, wherein: [0013] N is 1; or [0014] N is an integer more
than 1, and intra-group transmission calibration pilot sequences
are transmitted over different frequency resources in respective
transmitting radio frequency channels in a group.
[0015] In an implementation, the determining the inter-channel
compensation coefficients of the respective transmitting radio
frequency channels according to the channel information of the M
groups of transmitting radio frequency channels includes: [0016]
selecting a reference channel from each group of transmitting radio
frequency channels respectively according to the channel
information of each group of transmitting radio frequency channels
to obtain M reference channels; [0017] transmitting inter-group
transmission calibration pilot sequences over the M reference
channels, and performing channel estimation on the M reference
channels according to feedback signals of the inter-group
transmission calibration pilot sequences received over the
calibration receiving channel to obtain channel information of the
M reference channels; [0018] revising the channel information of
the group of transmitting radio frequency channels corresponding to
each reference channel respectively according to the channel
information of each reference channel; and [0019] determining the
inter-channel compensation coefficient of each transmitting radio
frequency channel according to the revised channel information of
each group of transmitting radio frequency channels.
[0020] In an implementation, the selecting a reference channel from
each group of transmitting radio frequency channels respectively
according to the channel information of each group of transmitting
radio frequency channels includes: [0021] for each group of
transmitting radio frequency channels, [0022] determining receive
power of each transmitting radio frequency channel in the group of
transmitting radio frequency channels; and [0023] determining
transmitting radio frequency channels with their receive power
being not below a first threshold as active transmitting radio
frequency channels, and selecting a reference channel from all the
active transmitting radio frequency channels in the group of
transmitting radio frequency channels according to the receive
power of all the active transmitting radio frequency channels in
the group of transmitting radio frequency channels.
[0024] In an implementation, the transmitting the inter-group
transmission calibration pilot sequences over the M reference
channels includes: [0025] mapping the inter-group transmission
calibration pilot sequences onto the sub-carriers in the entire
operating bandwidth of each reference channel, wherein the spacing
between sub-carriers to which each reference channel is mapped is a
first sub-carrier offset more than or equal to M, and the spacing
between sub-carriers to which two adjacent reference channels are
mapped is a second sub-carrier offset less than the first
sub-carrier offset.
[0026] In an implementation, the transmitting the inter-group
transmission calibration pilot sequences over the M reference
channels includes: [0027] transmitting the inter-group transmission
calibration pilot sequences over the M reference channels in a
transmission timeslot of the inter-group transmission calibration
pilot sequences in the current calibration period, wherein the
inter-group transmission calibration pilot sequences are
transmitted over different frequency resources of the M reference
channels.
[0028] In an implementation, the performing channel estimation on
the M reference channels according to the feedback signals of the
inter-group transmission calibration pilot sequences received over
the calibration receiving channel includes: [0029] performing
channel estimation on the M reference channels according to the
feedback signals of the inter-group transmission calibration pilot
sequences received over the calibration receiving channel, to
obtain channel information corresponding to the sub-carriers to
which the inter-group transmission calibration pilot sequences are
mapped over each reference channel; and [0030] performing
interpolation according to the channel information corresponding to
the sub-carriers to which the inter-group transmission calibration
pilot sequences are mapped over each reference channel, to obtain
channel information corresponding to all the sub-carriers over each
reference channel.
[0031] In an implementation, the revising the channel information
of the group of transmitting radio frequency channels corresponding
to each reference channel respectively according to the channel
information of each reference channel includes: [0032] for each
group of transmitting radio frequency channels, [0033] calculating
a ratio of channel information obtained based upon the inter-group
transmission calibration pilot sequences, to channel information
based upon the intra-group transmission calibration pilot
sequences, of the reference channel of the group of transmitting
radio frequency channels as a revision coefficient corresponding to
the group of transmitting radio frequency channels; and [0034]
calculating a product of the revision coefficient corresponding to
the group of transmitting radio frequency channels, and the channel
information of each transmitting radio frequency channel in the
group of transmitting radio frequency channels obtained based upon
the intra-group transmission calibration pilot sequences as revised
channel information of each transmitting radio frequency channel in
the group of transmitting radio frequency channels.
[0035] In an implementation, the performing channel estimation on
the respective groups of transmitting radio frequency channels
according to the feedback signals of the intra-group transmission
calibration pilot sequences received over the calibration receiving
channel to obtain the channel information of the M groups of
transmitting radio frequency channels includes: [0036] performing
channel estimation on each group of transmitting radio frequency
channels according to the feedback signals of the intra-group
transmission calibration pilot sequences received over the
calibration receiving channel, to obtain channel information
corresponding to the sub-carriers to which the intra-group
transmission calibration pilot sequences are mapped over each group
of transmitting radio frequency channels; and [0037] performing
interpolation according to the channel information corresponding to
the sub-carriers to which the intra-group transmission calibration
pilot sequences are mapped over each group of transmitting radio
frequency channels, to obtain channel information corresponding to
all the sub-carriers over each group of transmitting radio
frequency channels.
[0038] In an implementation, the transmitting the intra-group
transmission calibration pilot sequences over the corresponding
groups of transmitting radio frequency channels includes: [0039]
mapping the intra-group transmission calibration pilot sequences
corresponding respectively to the respective groups of transmitting
radio frequency channels onto the sub-carriers in the entire
operating bandwidth of the transmitting radio frequency channels,
wherein the spacing between the sub-carriers to which the
respective transmitting radio frequency channels are mapped is a
third sub-carrier offset which is more than or equal to the number
of channels in a group of transmitting radio frequency channels,
and the spacing between sub-carriers to which two adjacent
transmitting radio frequency channels are mapped is a fourth
sub-carrier offset which is less than the third sub-carrier
offset.
[0040] In an implementation, the transmission timeslots are guard
timeslots; and a first transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in a first group of transmitting radio frequency
channels, and a second transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in a second group of transmitting radio frequency
channels are two adjacent guard timeslots, or the first
transmission timeslot is spaced from the second transmission
timeslot by X guard timeslots, wherein the first group of
transmitting radio frequency channels, and the second group of
transmitting radio frequency channels are any two groups of
transmitting radio frequency channels with adjacent transmission
timeslots of their intra-group transmission calibration pilot
sequences, and X is an integer more than or equal to 1.
[0041] In the technical solutions according to the embodiments of
the invention, the transmitting radio frequency channels in the
array of antennas are grouped, and for each group of transmitting
radio frequency channels, intra-group transmission calibration
pilot sequences are transmitted only in a transmission timeslot
corresponding to the group, that is, intra-group transmission
calibration pilot sequences are transmitted in a transmission
timeslot over only one group of transmitting radio frequency
channels; and as compared with transmission calibration pilot
sequences being transmitted in a timeslot over all the transmitting
radio frequency channels in the array of antennas, the number of
radio frequency channels over which calibration pilot sequences are
transmitted in a timeslot can be reduced, so that the length of an
intra-group transmission calibration pilot sequence mapped onto
each transmitting radio frequency channel in channel estimation can
be increased to thereby improve the precision of the determined
inter-channel compensation coefficients of the respective
transmitting radio frequency channels.
[0042] An embodiment of the invention provides an apparatus for
calibrating an antenna, the apparatus including: [0043] an
obtaining unit configured to obtain information about grouping of
transmitting radio frequency channels, wherein the transmitting
radio frequency channels in an array of antennas are grouped into M
groups, and M is an integer more than 1; [0044] a first processing
unit configured to transmit intra-group transmission calibration
pilot sequences corresponding respectively to the respective groups
of transmitting radio frequency channels over the corresponding
groups of transmitting radio frequency channels respectively in
transmission timeslots of the intra-group transmission calibration
pilot sequences, and to perform channel estimation on the
respective groups of transmitting radio frequency channels
according to feedback signals of the intra-group transmission
calibration pilot sequences received over a calibration receiving
channel to obtain channel information of the M groups of
transmitting radio frequency channels, wherein there are different
transmission timeslots of intra-group transmission calibration
pilot sequences corresponding to different groups; and [0045] a
first determining unit configured to determine inter-channel
compensation coefficients of the respective transmitting radio
frequency channels according to the channel information of the M
groups of transmitting radio frequency channels.
[0046] In an implementation, each group of transmitting radio
frequency channels includes N transmitting radio frequency
channels, wherein: [0047] N is 1; or [0048] N is an integer more
than 1, and intra-group transmission calibration pilot sequences
are transmitted over different frequency resources in respective
transmitting radio frequency channels in a group.
[0049] In an implementation, the first determining unit includes:
[0050] a selecting unit configured to select a reference channel
from each group of transmitting radio frequency channels
respectively according to the channel information of each group of
transmitting radio frequency channels to obtain M reference
channels; [0051] a second processing unit configured to transmit
inter-group transmission calibration pilot sequences over the M
reference channels, and to perform channel estimation on the M
reference channels according to feedback signals of the inter-group
transmission calibration pilot sequences received over the
calibration receiving channel to obtain channel information of the
M reference channels; and [0052] a second determining unit
configured to revise the channel information of the group of
transmitting radio frequency channels corresponding to each
reference channel respectively according to the channel information
of each reference channel; and to determine the inter-channel
compensation coefficient of each transmitting radio frequency
channel according to the revised channel information of each group
of transmitting radio frequency channels.
[0053] In an implementation, the selecting unit is configured:
[0054] for each group of transmitting radio frequency channels,
[0055] to determine receive power of each transmitting radio
frequency channel in the group of transmitting radio frequency
channels; and [0056] to determine transmitting radio frequency
channels with their receive power being not below a first threshold
as active transmitting radio frequency channels, and to select a
reference channel from all the active transmitting radio frequency
channels in the group of transmitting radio frequency channels
according to the receive power of all the active transmitting radio
frequency channels in the group of transmitting radio frequency
channels.
[0057] In an implementation, the second processing unit is further
configured: [0058] to map the inter-group transmission calibration
pilot sequences onto the sub-carriers in the entire operating
bandwidth of each reference channel, wherein the spacing between
sub-carriers to which each reference channel is mapped is a first
sub-carrier offset more than or equal to M, and the spacing between
sub-carriers to which two adjacent reference channels are mapped is
a second sub-carrier offset less than the first sub-carrier
offset.
[0059] In an implementation, the second processing unit is further
configured: [0060] to transmit the inter-group transmission
calibration pilot sequences over the M reference channels in a
transmission timeslot of the inter-group transmission calibration
pilot sequences in the current calibration period, wherein the
inter-group transmission calibration pilot sequences are
transmitted over different frequency resources of the M reference
channels.
[0061] In an implementation, the second processing unit is further
configured: [0062] to perform channel estimation on the M reference
channels according to the feedback signals of the inter-group
transmission calibration pilot sequences received over the
calibration receiving channel, to obtain channel information
corresponding to the sub-carriers to which the inter-group
transmission calibration pilot sequences are mapped over each
reference channel; and [0063] to perform interpolation according to
the channel information corresponding to the sub-carriers to which
the inter-group transmission calibration pilot sequences are mapped
over each reference channel, to obtain channel information
corresponding to all the sub-carriers over each reference
channel.
[0064] In an implementation, the second processing unit is further
configured: [0065] for each group of transmitting radio frequency
channels, [0066] to calculate a ratio of channel information
obtained based upon the inter-group transmission calibration pilot
sequences, to channel information based upon the intra-group
transmission calibration pilot sequences, of the reference channel
of the group of transmitting radio frequency channels as a revision
coefficient corresponding to the group of transmitting radio
frequency channels; and [0067] to calculate a product of the
revision coefficient corresponding to the group of transmitting
radio frequency channels, and the channel information of each
transmitting radio frequency channel in the group of transmitting
radio frequency channels obtained based upon the intra-group
transmission calibration pilot sequences as revised channel
information of each transmitting radio frequency channel in the
group of transmitting radio frequency channels.
[0068] In an implementation, the second processing unit is further
configured: [0069] to perform channel estimation on each group of
transmitting radio frequency channels according to the feedback
signals of the intra-group transmission calibration pilot sequences
received over the calibration receiving channel, to obtain channel
information corresponding to the sub-carriers to which the
intra-group transmission calibration pilot sequences are mapped
over each group of transmitting radio frequency channels; and
[0070] to perform interpolation according to the channel
information corresponding to the sub-carriers to which the
intra-group transmission calibration pilot sequences are mapped
over each group of transmitting radio frequency channels, to obtain
channel information corresponding to all the sub-carriers over each
group of transmitting radio frequency channels.
[0071] In an implementation, the first processing unit is
configured: [0072] to map the intra-group transmission calibration
pilot sequences corresponding respectively to the respective groups
of transmitting radio frequency channels onto the sub-carriers in
the entire operating bandwidth of the transmitting radio frequency
channels, wherein the spacing between the sub-carriers to which the
respective transmitting radio frequency channels are mapped is a
third sub-carrier offset which is more than or equal to the number
of channels in a group of transmitting radio frequency channels,
and the spacing between sub-carriers to which two adjacent
transmitting radio frequency channels are mapped is a fourth
sub-carrier offset which is less than the third sub-carrier
offset.
[0073] In an implementation, the transmission timeslots are guard
timeslots; and a first transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in a first group of transmitting radio frequency
channels, and a second transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in a second group of transmitting radio frequency
channels are two adjacent guard timeslots, or the first
transmission timeslot is spaced from the second transmission
timeslot by X guard timeslots, wherein the first group of
transmitting radio frequency channels, and the second group of
transmitting radio frequency channels are any two groups of
transmitting radio frequency channels with adjacent transmission
timeslots of their intra-group transmission calibration pilot
sequences, and X is an integer more than or equal to 1.
[0074] In the technical solutions according to the embodiments of
the invention, the transmitting radio frequency channels in the
array of antenna are grouped into M groups, and transmission
calibration is performed in such a way that the intra-group
transmission calibration pilot sequences of the corresponding
groups are transmitted over the transmitting radio frequency
channels in the corresponding groups respectively in the
transmission timeslots corresponding respectively to the respective
groups of transmitting radio frequency channels, channel estimation
is performed on each group of transmitting radio frequency channels
according to the feedback signals of the intra-group transmission
calibration pilot sequences received over the calibration receiving
channel, to obtain the channel information of the M groups of
transmitting radio frequency channels, where the transmission
timeslots of the intra-group transmission calibration pilot
sequences corresponding to the different groups are different from
each other; and the inter-channel compensation coefficient of each
transmitting radio frequency channel is determined according to the
channel information of the M groups of transmitting radio frequency
channels. The transmitting radio frequency channels in the array of
antennas are grouped, and for each group of transmitting radio
frequency channels, intra-group transmission calibration pilot
sequences are transmitted only in a transmission timeslot
corresponding to the group, that is, intra-group transmission
calibration pilot sequences are transmitted in a transmission
timeslot over only one group of transmitting radio frequency
channels, so as compared with transmission calibration pilot
sequences being transmitted in a timeslot over all the transmitting
radio frequency channels in the array of antennas, the number of
radio frequency channels over which calibration pilot sequences are
transmitted in a timeslot can be reduced, so that the length of an
intra-group transmission calibration pilot sequence mapped onto
each transmitting radio frequency channel in channel estimation can
be increased to thereby improve the precision of the determined
inter-channel compensation coefficients of the respective
transmitting radio frequency channels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0075] In order to make the technical solutions in the embodiments
of the invention more apparent, the drawings to be used in a
description of the embodiments will be briefly introduced below,
and apparently the drawings to be described below are merely
illustrative of some embodiments of the invention, and those
ordinarily skilled in the art can further derive from these
drawings other drawings without any inventive effort. In the
drawings:
[0076] FIG. 1 is a schematic flow chart of a method for calibrating
an antenna according to an embodiment of the invention;
[0077] FIG. 2 is a schematic diagram of mapping intra-group
transmission calibration pilot sequences onto sub-carriers in the
entire operating bandwidth of transmitting radio frequency channels
according to an embodiment of the invention;
[0078] FIG. 3 is a schematic diagram of transmitting each group of
transmission calibration pilot sequences in a transmission timeslot
according to an embodiment of the invention;
[0079] FIG. 4 is a schematic diagram of transmitting radio
frequency channels according to an embodiment of the invention;
[0080] FIG. 5 is a schematic flow chart of another method for
calibrating an antenna according to an embodiment of the
invention;
[0081] FIG. 6 is a schematic diagram of mapping inter-group
transmission calibration pilot sequences onto sub-carriers in the
entire operating bandwidth of reference channels according to an
embodiment of the invention;
[0082] FIG. 7 is a schematic structural diagram of an apparatus for
calibrating an antenna according to an embodiment of the invention;
and
[0083] FIG. 8 is a schematic structural diagram of another
apparatus for calibrating an antenna according to an embodiment of
the invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0084] In order to make the objects, technical solutions, and
advantageous effects of the invention more apparent, the invention
will be described below in further details with reference to the
drawings, and the embodiments thereof. It shall be appreciated that
the particular embodiments described here are merely intended to
explain but not to limit the invention.
[0085] The embodiments of the invention are applicable to
transmission calibration on an antenna. The embodiments of the
invention are applicable to a system including a number of
antennas. Typically there is a transmitting radio frequency channel
of each antenna element, and the embodiments of the invention will
not be limited to any particular number of transmitting radio
frequency channels for an antenna element.
[0086] In the embodiments of the invention, transmitting radio
frequency channels in an array of antennas are grouped into M
groups, where M is an integer more than 1. The number of
transmitting radio frequency channels in one group may or may not
be the same as the number of transmitting radio frequency channels
in another group. If there is one transmitting radio frequency
channel for one antenna element, for example, then one or more rows
of antenna elements may be grouped into one group, or one or more
columns of antenna elements may be grouped into one group, but the
embodiments of the invention will not be limited to any particular
grouping pattern. For example, for an array of antennas including Q
antenna elements, transmitting radio frequency channels can be
grouped into M groups of transmitting radio frequency channels,
where there are N transmitting radio frequency channels in each
group of transmitting radio frequency channels, and
M.times.N=Q.
[0087] In the embodiments of the invention, the transmission
calibration pilot sequences for transmission calibration can
include intra-group transmission calibration pilot sequences.
Furthermore the transmission calibration pilot sequences for
transmission calibration can include inter-group transmission
calibration pilot sequences. The intra-group transmission
calibration pilot sequences and the inter-group transmission
calibration pilot sequences can be used as described below.
[0088] The intra-group transmission calibration pilot sequences and
the inter-group transmission calibration pilot sequences can be
determined in a number of methods in the embodiments of the
invention.
[0089] A method for determining an intra-group transmission
calibration pilot sequence c.sup.In(i) according to an embodiment
of the invention will be described below in details.
[0090] Firstly the intra-group transmission calibration pilot
sequences can be Zadoff-Chu (ZC) sequences with good correlation.
In a system operating bandwidth, the total number of sub-carriers
in the frequency domain over all the transmitting radio frequency
channels is determined in Equation (1) of:
K=N.sub.RBN.sub.sc.sup.RB (1)
[0091] In Equation (1) above:
[0092] K represents the total number of sub-carriers in the
frequency domain over all the transmitting radio frequency
channels; and
[0093] N.sub.RB represents the number of resource blocks in a
system operating bandwidth of a single transmitting radio frequency
channel, and N.sub.sc.sup.RB represents the number of sub-carriers
in each resource block.
[0094] Secondly the length of an intra-group transmission
calibration pilot sequence is determined in Equation (2) of:
N sc In = K .DELTA. d sc In ( 2 ) ##EQU00001##
[0095] In Equation (2) above:
[0096] N.sub.sc.sup.In represents the length of an intra-group
transmission calibration pilot sequence;
[0097] K represents the total number of sub-carriers; and
[0098] .DELTA.d.sub.sc.sup.In represents the spacing between
sub-carriers to which each transmitting radio frequency channel is
mapped, i.e., the interval between two adjacent intra-group
transmission calibration pilot sequences in a single transmitting
radio frequency channel; and .left brkt-bot..cndot..right brkt-bot.
represents rounding down.
[0099] Particularly if the intra-group transmission calibration
pilot sequences are mapped into each group of transmitting radio
frequency channels, then the intra-group transmission calibration
pilot sequences will be spread throughout the operating bandwidth,
for example, the operating bandwidth of each transmitting radio
frequency channel can be 20 MHz or 40 MHz; and also the interval
between two adjacent intra-group transmission calibration pilot
sequences in a single transmitting radio frequency channel will be
determined, and in order to ensure the intra-group transmission
calibration pilot sequences to be mapped respectively onto
different frequency resources of each radio frequency channel in
the frequency division mode, the interval between two adjacent
intra-group transmission calibration pilot sequences will be more
than or equal to N, where N represents the total number of
transmitting radio frequency channels in each group of transmitting
radio frequency channels.
[0100] Lastly the intra-group transmission calibration pilot
sequences are determined in Equation (3) of:
c.sup.In(i)=x.sub.g(w) (3)
[0101] In Equation (3) above:
[0102] c.sup.In(i) represents the i-th intra-group transmission
calibration pilot sequence;
[0103] Where i represents an index, i is a positive integer,
0.ltoreq.i<N.sub.sc.sup.In, and N.sub.sc.sup.In represents the
length of the intra-group transmission calibration pilot
sequence;
0 .ltoreq. w .ltoreq. N ZC In - 1 , and x g ( w ) = e - j .pi. g w
( w + 1 ) N ZC In ; ##EQU00002##
and .left brkt-bot..cndot..right brkt-bot. represents rounding
down;
[0104] N.sub.ZC.sup.In represents the length of a ZC sequence for
the intra-group transmission calibration pilot sequence, and
N.sub.ZC.sup.In is the largest prime number satisfying the
condition N.sub.ZC.sup.In.ltoreq.N.sub.sc.sup.In;
g=.left brkt-bot.g+1/2.right brkt-bot.+v(-1).sup..left
brkt-bot.2g.right brkt-bot.
g=N.sub.ZC.sup.In(u+1)/31; and [0105] u=0 [0106] v=0
[0107] Furthermore w=(i mod N.sub.ZC.sup.In), and w=(i mod
N.sub.ZC.sup.In) is substituted into Equation (3) above, thus
resulting in Equation (4):
c.sup.In(i)=x.sub.q(i mod N.sub.ZC.sup.In) (4)
[0108] In Equation (4) above, mod represents taking a
remainder.
[0109] The method above for determining an intra-group transmission
calibration pilot sequence will be described below by way of a
particular example.
[0110] If the operating bandwidth of each transmitting radio
frequency channel is 20 MHz, the number of sub-carriers in the
frequency domain in the transmitting radio frequency channel in the
operating bandwidth is K=1200, and the number of transmitting radio
frequency channels in each group of transmitting radio frequency
channels is N=8, then .DELTA.d.sub.sc.sup.In=12 may be set to
thereby satisfy .DELTA.d.sub.sc.sup.In.gtoreq.N as required.
[0111] Firstly the length N.sub.sc.sup.In of an intra-group
transmission calibration pilot sequence is determined in Equation
(2) above:
N sc In = K .DELTA. d sc In = 1200 12 = 100 ##EQU00003##
[0112] Next the length N.sub.ZC.sup.In of a ZC sequence for the
intra-group transmission calibration pilot sequence is determined;
and N.sub.ZC.sup.In is the largest prime number satisfying the
condition N.sub.ZC.sup.In.ltoreq.N.sub.sc.sup.In, and
N.sub.sc.sup.In=100, so the largest prime number satisfying the
condition N.sub.ZC.sup.In.ltoreq.N.sub.sc.sup.In is 99, that is,
N.sub.ZC.sup.In=99.
[0113] Thereafter all the intra-group transmission calibration
pilot sequences in each transmitting radio frequency channel are
determined in Equation (3) and Equation (4), and particularly all
the intra-group transmission calibration pilot sequences in each
transmitting radio frequency channel are c.sup.In(0), c.sup.In(1),
c.sup.In(2), . . . c.sup.In(i) . . . c.sup.In(N.sub.sc.sup.In-1)
respectively.
[0114] A method for determining an inter-group transmission
calibration pilot sequence of a reference channel according to an
embodiment of the invention will be described below in details.
[0115] Firstly a reference channel is a transmitting radio
frequency channel selected from each group of transmitting radio
frequency channels, so for each reference channel, the number K of
sub-carriers in the frequency domain over the transmitting radio
frequency channel in a system operating bandwidth is still
determined in Equation (1) above.
[0116] Secondly the length of the inter-group transmission
calibration pilot sequence of the reference channel is determined
in Equation (5) of:
N sc Ref = K .DELTA. d sc Ref ( 24 ) ##EQU00004##
[0117] In Equation (5) above:
[0118] N.sub.sc.sup.Ref represents the length of the inter-group
transmission calibration pilot sequence of the reference
channel;
[0119] K represents the total number of sub-carriers; and
[0120] .DELTA.d.sub.sc.sup.Ref represents the interval between two
adjacent inter-group transmission calibration pilot sequences in a
transmitting radio frequency channel of a single reference channel;
and .left brkt-bot..cndot..right brkt-bot. represents rounding
down.
[0121] Particularly if the inter-group transmission calibration
pilot sequences are mapped onto transmitting radio frequency
channels of M reference channels, then the inter-group transmission
calibration pilot sequences will be spread throughout the operating
bandwidth, for example, the operating bandwidths of transmitting
radio frequency channels of each reference channel can be 20 MHz or
40 MHz; and also the interval between two adjacent inter-group
transmission calibration pilot sequences in transmitting radio
frequency channels of a single reference channel will be
determined, and in order to ensure the inter-group transmission
calibration pilot sequences to be mapped respectively onto
different frequency resources of radio frequency channels of each
reference channel in the frequency division mode, the interval
between two adjacent inter-group transmission calibration pilot
sequences will be more than or equal to M, where M represents the
total number of groups of transmitting radio frequency
channels.
[0122] Lastly the inter-group transmission calibration pilot
sequences are determined in Equation (6) of:
c.sup.Ref(j)=x.sub.i(r) (6)
[0123] In Equation (6) above:
[0124] j represents an index, 0.ltoreq.j<N.sub.sc.sup.Ref, and
N.sub.sc.sup.Ref represents the length of an inter-group
transmission calibration pilot sequence;
[0125] c.sup.Ref(j) represents the j-th inter-group transmission
calibration pilot sequence corresponding to the reference
channel;
0 .ltoreq. r .ltoreq. ( N ZC Ref - 1 ) , and x l ( r ) = e - j .pi.
l r ( r + 1 ) N ZC Ref ; ##EQU00005##
[0126] N.sub.ZC.sup.Ref represents the length of a ZC sequence for
the inter-group transmission calibration pilot sequence, and
N.sub.ZC.sup.Ref is the largest prime number satisfying the
condition N.sub.ZC.sup.Ref.ltoreq.N.sub.sc.sup.Ref;
l=.left brkt-bot.l+1/2.right brkt-bot.+v(-1).sup..left
brkt-bot.2l.right brkt-bot.
l=N.sub.ZC.sup.Ref(u+1)/31; and [0127] u=0 [0128] v=0
[0129] Furthermore r=(j mod N.sub.ZC.sup.Ref), and r=(j mod
N.sub.ZC.sup.Ref) is substituted into Equation (6) above, thus
resulting in Equation (7):
C.sup.Ref(j)=x.sub.q(j mod N.sub.ZC.sup.Ref) (7)
[0130] In Equation (7) above, mod represents taking a
remainder.
[0131] Particularly all the inter-group transmission calibration
pilot sequences in each reference channel are determined in
Equation (6) and Equation (7), and particularly all the inter-group
transmission calibration pilot sequences in each transmitting radio
frequency channel are c.sup.Ref(0), c.sup.Ref(1), c.sup.Ref(2), . .
. c.sup.Ref(j) . . . c.sup.Ref(N.sub.sc.sup.In-1) respectively.
[0132] In the embodiments of the invention, the intra-group
transmission calibration pilot sequences and the inter-group
transmission calibration pilot sequences can be determined in a
number of implementations without any limitation to the
implementations described above. In an implementation, each group
of transmitting radio frequency channels corresponds separately to
one intra-group transmission calibration pilot sequence, and
different groups of transmitting radio frequency channels
correspond to different intra-group transmission calibration pilot
sequences. Alternatively each group of transmitting radio frequency
channels may correspond to the same intra-group transmission
calibration pilot sequence. In the embodiments of the invention,
the intra-group transmission calibration pilot sequences and the
inter-group transmission calibration pilot sequences can be
determined at any time as decided by the user. For example, the
intra-group transmission calibration pilot sequences may be
determined in advance, and after channel estimation is performed on
each group of transmitting radio frequency channels, if channel
estimation needs to be performed on the reference channels, then
the inter-group transmission calibration pilot sequences may be
further determined.
[0133] FIG. 1 illustrates a method for calibrating an antenna
according to an embodiment of the invention, and as illustrated in
FIG. 1, the method includes the operations of:
[0134] The operation 101 of obtaining information about grouping of
transmitting radio frequency channels, where the transmitting radio
frequency channels in an array of antennas are grouped into M
groups, and M is an integer more than 1;
[0135] The operation 102 of transmitting intra-group transmission
calibration pilot sequences corresponding respectively to the
respective groups of transmitting radio frequency channels over the
corresponding groups of transmitting radio frequency channels
respectively in transmission timeslots of the intra-group
transmission calibration pilot sequences, and performing channel
estimation on the respective groups of transmitting radio frequency
channels according to feedback signals of the intra-group
transmission calibration pilot sequences received over a
calibration receiving channel to obtain channel information of the
M groups of transmitting radio frequency channels, where there are
different transmission timeslots of intra-group transmission
calibration pilot sequences corresponding to different groups;
and
[0136] The operation 103 of determining inter-channel compensation
coefficients of the respective transmitting radio frequency
channels according to the channel information of the M groups of
transmitting radio frequency channels.
[0137] In an implementation, each group of transmitting radio
frequency channels includes N transmitting radio frequency
channels, where N is 1, or N is an integer more than 1. If N is an
integer more than 1, then intra-group transmission calibration
pilot sequences will be transmitted over different frequency
resources in respective transmitting radio frequency channels in a
group, that is, intra-group transmission calibration pilot
sequences will be transmitted in a group in the frequency division
mode.
[0138] Particularly if N is 1, that is, there is only one
transmitting radio frequency channel in a group, then intra-group
transmission calibration pilot sequences will be transmitted in
respective transmission timeslots over the respective transmitting
radio frequency channels in the time division mode over as
described in the embodiment above. At this time, the intra-group
transmission calibration pilot sequences corresponding to the
respective transmitting radio frequency channels can be mapped onto
the frequency resources of the transmitting radio frequency
channels. In order to improve the accuracy of the obtained channel
information, a larger number of intra-group transmission
calibration pilot sequences can be mapped onto the frequency
resources of the transmitting radio frequency channels, or at most
an intra-group transmission calibration pilot sequence can be
mapped onto each of the frequency resources of the transmitting
radio frequency channels, thus improving the accuracy of channel
estimation on the transmitting radio frequency channels.
[0139] On the other hand, if N is an integer more than 1, then
since each group of transmitting radio frequency channels includes
a number of transmitting radio frequency channels, and intra-group
transmission calibration pilot sequences corresponding to all the
respective transmitting radio frequency channels in the group of
transmitting radio frequency channels need to be transmitted in a
transmission timeslot, the intra-group transmission calibration
pilot sequences corresponding to the group of transmitting radio
frequency channels may be mapped onto different frequency resources
of the group of transmitting radio frequency channels in the
frequency division mode, so that intra-group transmission
calibration pilot sequences are transmitted over different
frequency resources in respective transmitting radio frequency
channels in a group. In another implementation, channel estimation
on a number of transmitting radio frequency channels in a group can
be performed in the code division mode.
[0140] In the embodiments of the invention, the transmitting radio
frequency channels in the array of antennas are grouped, and for
each group of transmitting radio frequency channels, intra-group
transmission calibration pilot sequences are transmitted only in a
transmission timeslot corresponding to the group, that is,
intra-group transmission calibration pilot sequences are
transmitted in a transmission timeslot over only one group of
transmitting radio frequency channels; and as compared with
transmission calibration pilot sequences being transmitted in a
timeslot over all the transmitting radio frequency channels in the
array of antennas, the number of radio frequency channels over
which calibration pilot sequences are transmitted in a timeslot can
be reduced in the embodiments of the invention, so that the length
of an intra-group transmission calibration pilot sequence which can
be mapped onto each radio frequency channel in a group is increased
accordingly. Furthermore the length of an intra-group transmission
calibration pilot sequence mapped in channel estimation on each
transmitting radio frequency channel can be increased to thereby
improve the precision of the inter-channel compensation
coefficients of the respective transmitting radio frequency
channels determined according to the channel information of the M
groups of transmitting radio frequency channels.
[0141] In an embodiment of the invention, each group of
transmitting radio frequency channels corresponds to an intra-group
transmission calibration pilot sequence, and transmission
calibration pilot sequences corresponding to different groups may
or may not be the same. The intra-group transmission calibration
pilot sequence corresponding to each group of transmitting radio
frequency channels is used for channel estimation on the group of
transmitting radio frequency channels.
[0142] In the operation 102, in an implementation, for the
intra-group transmission calibration pilot sequences mapped onto
the respective groups of transmitting radio frequency channels, the
intra-group transmission calibration pilot sequences corresponding
respectively to the respective groups of transmitting radio
frequency channels are mapped onto the sub-carriers in the entire
operating bandwidth of the transmitting radio frequency channels,
where the spacing between the sub-carriers to which the respective
transmitting radio frequency channels are mapped is a third
sub-carrier offset which is more than or equal to the number of
channels in a group of transmitting radio frequency channels, and
the spacing between sub-carriers to which two adjacent transmitting
radio frequency channels are mapped is a fourth sub-carrier offset
which is less than the third sub-carrier offset.
[0143] FIG. 2 is a schematic diagram of mapping intra-group
transmission calibration pilot sequences onto sub-carriers in the
entire operating bandwidth of transmitting radio frequency channels
according to an embodiment of the invention. As illustrated in the
schematic diagram of a group of transmitting radio frequency
channels, for example, the group of transmitting radio frequency
channels includes transmitting radio frequency channels of five
antennas, which are a first transmitting radio frequency channel
201, a second transmitting radio frequency channel 202, a third
transmitting radio frequency channel 203, a fourth transmitting
radio frequency channel 204, and a fifth transmitting radio
frequency channel 205, where each transmitting radio frequency
channel corresponds to an operating bandwidth 209 including all the
sub-carriers in the corresponding transmitting radio frequency
channel. The spacing between sub-carriers to which each
transmitting radio frequency channel is mapped is a third
sub-carrier offset 210.
[0144] Particularly in FIG. 2, the spacing between a first
intra-group transmission calibration pilot sequence 206 and a
second intra-group transmission calibration pilot sequence 207
mapped in the first transmitting radio frequency channel 201 is the
third sub-carrier offset 210. The spacing between sub-carriers to
which two adjacent transmitting radio frequency channels are mapped
is a fourth sub-carrier offset 211. Particularly in FIG. 2, the
spacing between the first intra-group transmission calibration
pilot sequence 206 in the first transmitting radio frequency
channel 201, and the first intra-group transmission calibration
pilot sequence 206 in the second transmitting radio frequency
channel 202 is the fourth sub-carrier offset 211.
[0145] All the intra-group transmission calibration pilot sequences
in a group corresponding to each group of transmitting radio
frequency channels as determined above are c.sup.Ref(0),
c.sup.Ref(1), c.sup.Ref(2), . . . c.sup.Ref(j) . . .
c.sup.Ref(N.sub.sc.sup.In-1) respectively, where c.sup.In(i)
represents the i-th intra-group transmission calibration pilot
sequence; and i represents an index, i is a positive integer,
0.ltoreq.i<N.sub.sc.sup.In, and N.sub.sc.sup.In represents the
length of an intra-group transmission calibration pilot sequence.
All the intra-group transmission calibration pilot sequences are
mapped respectively into each transmitting radio frequency channel.
As illustrated in FIG. 2, firstly c.sup.In(0), i.e., the first
intra-group transmission calibration pilot sequence 206, is mapped
into each transmitting radio frequency channel, next c.sup.In(1)
i.e., the second intra-group transmission calibration pilot
sequence 207, is mapped into each transmitting radio frequency
channel, and the determined intra-group transmission calibration
pilot sequences are mapped respectively into each transmitting
radio frequency channel sequentially until lastly
C.sup.In(N.sub.sc.sup.In-1), i.e., the (N.sub.sc.sup.In-1)-th
intra-group transmission calibration pilot sequence, is mapped into
each transmitting radio frequency channel.
[0146] As can be apparent from FIG. 2, if intra-group transmission
calibration pilot sequences corresponding respectively to each
group of transmitting radio frequency channels are mapped onto
sub-carriers in the entire operating bandwidth in the frequency
division mode, then the distance denoted by the third sub-carrier
offset 210 in FIG. 2 may be the spacing between sub-carriers to
which each transmitting radio frequency channel is mapped. Since an
intra-group transmission calibration pilot sequence needs to be
mapped onto a different frequency resource in each of the
transmitting radio frequency channels in the group of transmitting
radio frequency channels in the third sub-carrier offset 210, the
spacing between sub-carriers to which each transmitting radio
frequency channel is mapped shall be more than or equal to 5 in
FIG. 2 so that there is an intra-group transmission calibration
pilot sequence mapped onto each of five transmitting radio
frequency channels, and each intra-group transmission calibration
pilot sequence is mapped onto a different frequency resource, in
the spacing of each third sub-carrier offset 210 in the group of
transmitting radio frequency channels in FIG. 2.
[0147] In an implementation, if the third sub-carrier offset 210 is
set larger, then the intra-group transmission calibration pilot
sequences mapped into the respective transmitting radio frequency
channels may be arranged uniformly in the third sub-carrier offset
210. For example, the fourth sub-carrier offset 211 illustrated in
FIG. 2 is the spacing of one sub-carrier. In an implementation, the
fourth sub-carrier offset 211 may alternatively be the spacing of
more than one sub-carrier, but the embodiments of the invention
will not be limited to any particular spacing.
[0148] FIG. 2 illustrates a mapping pattern of intra-group
transmission calibration pilot sequences in only one group, and
there are M groups of transmitting radio frequency channels in
total in the embodiments of the invention, but the intra-group
transmission calibration pilot sequences in the other groups may or
may not be mapped in substantially the same pattern as the pattern
in which the intra-group transmission calibration pilot sequences
in the group are mapped as illustrated in FIG. 2, and the
embodiments of the invention will not be limited thereto.
[0149] Furthermore after intra-group transmission calibration pilot
sequences corresponding respectively to each group of transmitting
radio frequency channels are mapped into the transmitting radio
frequency channels in the corresponding group in the frequency
division mode, the intra-group transmission calibration pilot
sequences corresponding respectively to each group of transmitting
radio frequency channels are transmitted respectively in a
transmission timeslot of the intra-group transmission calibration
pilot sequences.
[0150] Particularly as illustrated in FIG. 3, FIG. 3 illustrates a
schematic diagram of transmitting each group of transmission
calibration pilot sequences in a transmission timeslot according to
an embodiment of the invention. FIG. 3 illustrates a number of
sub-frames 303, and also a number of transmission timeslots, e.g.,
a first transmission timeslot 305, a second transmission timeslot
307, a third transmission timeslot 308, etc. Intra-group
transmission calibration pilot sequences mapped onto at most one
group of transmitting radio frequency channels are transmitted in a
timeslot. A group of transmission calibration pilot sequences is
transmitted in each transmission timeslot for antenna calibration
throughout a transmission calibration period 301. In a frame
structure, a preceding frame 304 to the transmission timeslot, and
a succeeding frame 306 to the transmission timeslot are sub-frames
in a special structure. If the transmission timeslot is a guard
timeslot, then the preceding frame 304 to the transmission timeslot
will be a downlink pilot timeslot, and the succeeding frame 306 to
the transmission timeslot will be an uplink pilot timeslot. In FIG.
3, if transmission calibration pilot sequences of a first group of
transmitting radio frequency channels are transmitted in the first
transmission timeslot 305, transmission calibration pilot sequences
of a second group of transmitting radio frequency channels are
transmitted in the second transmission timeslot 307, and
transmission calibration pilot sequences of the M-th group of
transmitting radio frequency channels are transmitted in the third
transmission timeslot 308, then the spacing between transmission
timeslots corresponding to two adjacent groups of transmitting
radio frequency channels will be an inter-group transmission
calibration offset 302.
[0151] In an implementation, in another transmission scheme,
transmission calibration pilot sequences of a first group of
transmitting radio frequency channels are transmitted in the first
transmission timeslot 305, no transmission calibration pilot
sequences of any one group of transmitting radio frequency channels
are transmitted in the second transmission timeslot 307, and
transmission calibration pilot sequences of each group of
transmitting radio frequency channels are transmitted sequentially
in the transmission timeslots until transmission calibration pilot
sequences of the M-th group of transmitting radio frequency
channels are transmitted in the third transmission timeslot 308,
that is, transmission timeslots corresponding to every two adjacent
groups of transmitting radio frequency channels can be spaced from
each other by one or more transmission timeslots. Particularly
there are a number of transmission schemes in which the
transmission calibration pilot sequences are transmitted in the
transmission timeslots as long as intra-group transmission
calibration pilot sequences mapped onto at most one group of
transmitting radio frequency channels are transmitted in a
timeslot.
[0152] In an implementation, the transmission timeslots are guard
timeslots; and the first transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in the first group of transmitting radio frequency
channels, and the second transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in the second group of transmitting radio frequency
channels are two adjacent transmission timeslots, or the first
transmission timeslot is spaced from the second transmission
timeslot by X guard timeslots, where the first group of
transmitting radio frequency channels, and the second group of
transmitting radio frequency channels are any two groups of
transmitting radio frequency channels with adjacent transmission
timeslots of their intra-group transmission calibration pilot
sequences, and X is an integer more than or equal to 1. In an
implementation, the interval between transmission timeslots of two
adjacent groups of transmitting radio frequency channels can be an
inter-group transmission calibration offset .DELTA.T.sup.In in an
embodiment of the invention.
[0153] Furthermore the array of antennas includes a calibration
receiving channel in addition to the antennas, each of which
corresponds to a transmitting radio frequency channel as
illustrated in FIG. 4. FIG. 4 illustrates a schematic diagram of
transmitting radio frequency channels according to an embodiment of
the invention, and in an embodiment of the invention, for example,
there are M groups of transmitting radio frequency channels in
total, each of which includes N transmitting radio frequency
channels. Then as illustrated in FIG. 4, a first group of
transmitting radio frequency channels 401 includes N transmitting
radio frequency channels in total, which are a transmitting radio
frequency channel 1 (406), a transmitting radio frequency channel 2
(407), . . . , and a transmitting radio frequency channel N (408)
respectively; a second group of transmitting radio frequency
channels 402 includes N transmitting radio frequency channels in
total, which are a transmitting radio frequency channel N+1 (409),
a transmitting radio frequency channel N+2 (410), . . . , and a
transmitting radio frequency channel 2N (411) respectively; . . . ,
and the M-th group of transmitting radio frequency channel 403
includes N transmitting radio frequency channels in total, which
are a transmitting radio frequency channel (M-1)*N+1 (412), a
transmitting radio frequency channel (M-1)*N+2 (413), . . . , and a
transmitting radio frequency channel M*N (414) respectively. FIG. 4
further illustrates a coupling network 405 and a calibration
receiving channel 404.
[0154] As illustrated in FIG. 4, after intra-group transmission
calibration pilot sequences corresponding to each group of
transmitting radio frequency channels are mapped onto the group of
transmitting radio frequency channels, the intra-group transmission
calibration pilot sequences are transmitted over the transmitting
radio frequency channels in the group in a transmission timeslot,
the intra-group transmission calibration pilot sequences
transmitted in the N transmitting radio frequency channels in the
group are processed over the coupling network 405, and channel
estimation is performed on the group of transmitting radio
frequency channels according to feedback signals of the intra-group
transmission calibration pilot sequences of the group received over
the calibration receiving channel 404.
[0155] A process of channel estimation on each group of
transmitting radio frequency channel will be described below in
details taking the first group of transmitting radio frequency
channels as an example. Those skilled in the art can appreciate
that channel estimation on the other groups of transmitting radio
frequency channels will be similar to that on the first group, so a
repeated description thereof will be omitted here.
[0156] Firstly the intra-group transmission calibration pilot
sequences corresponding to the first group of transmitting radio
frequency channels are determined as described above. In an
embodiment of the invention, for example, each group of
transmitting radio frequency channels corresponds to the same
intra-group transmission calibration pilot sequences, but those
skilled in the art can alternatively select different intra-group
transmission calibration pilot sequences respectively for the other
groups of transmitting radio frequency channels.
[0157] Secondly a pattern in which the intra-group transmission
calibration pilot sequences corresponding to the first group of
transmitting radio frequency channels are mapped in the first group
of transmitting radio frequency channels is determined. In an
implementation, the spacing between sub-carriers to which each
transmitting radio frequency channel is mapped, and the spacing
between sub-carriers to which two adjacent transmitting radio
frequency channels are mapped are determined as described
above.
[0158] Thirdly the intra-group transmission calibration pilot
sequences corresponding to the first group of transmitting radio
frequency channels are mapped in each transmitting radio frequency
channel in the first group of transmitting radio frequency channels
at the spacing between sub-carriers to which each transmitting
radio frequency channel is mapped, and the spacing between
sub-carriers to which two adjacent transmitting radio frequency
channels, and transmission signals of N transmitting radio
frequency channels are generated in Equation (8) of:
s.sub.n.sup.In(k)=c.sup.In(i) (8)
[0159] In Equation (8) above:
[0160] s.sub.n.sup.In(k) represents a transmission signal of the
k-th sub-carrier of the n-th transmitting radio frequency channel
in each group of transmitting radio frequency channels;
[0161] i represents an index, i is a positive integer,
0.ltoreq.i<N.sub.sc.sup.In, and N.sub.sc.sup.In represents the
length of an intra-group transmission calibration pilot
sequence;
[0162] c.sup.In(i) represents the i-th intra-group transmission
calibration pilot sequence;
[0163] n represents the index of each transmitting radio frequency
channel in each group of transmitting radio frequency channels, n
is a positive integer, and the value of n ranges from 1 to N;
and
[0164] k represents the index of each sub-carrier, and
k=i.DELTA.d.sub.sc.sup.In+.DELTA.f.sub.sc.sup.In(n-1), where
.DELTA.d.sub.sc.sup.In represents the spacing between sub-carriers
to which each transmitting radio frequency channel is mapped, and
.DELTA.f.sub.sc.sup.In represents the spacing between sub-carriers
to which two adjacent transmitting radio frequency channels are
mapped.
[0165] Particularly the transmission signals s.sub.n.sup.In(k) of
the N transmitting radio frequency channels can be generated by a
signal processor which may be located at the radio frequency side
or the baseband side in a physical entity. Particularly since the
first group of transmitting radio frequency channels includes N
transmitting radio frequency channels, the series of
s.sub.n.sup.In(k) can be written as s.sub.1.sup.In(k),
s.sub.2.sup.In(k), s.sub.3.sup.In(k) . . . , s.sub.N.sup.In(k).
[0166] Fourthly in the first to N-th transmitting radio frequency
channels in the first group of transmitting radio frequency
channels, Inverse Fast Fourier Transformation (IFFT) is performed
respectively on s.sub.1.sup.In(k), s.sub.2.sup.In(k),
s.sub.3.sup.In(k) . . . , s.sub.N.sup.In(k), and a corresponding
Cyclic Prefix (CP) is added thereto to form time domain signals
x.sub.1.sup.In(t), x.sub.2.sup.In(t), x.sub.3.sup.In(t), . . . ,
x.sub.n.sup.In(t), . . . , x.sub.N.sup.In(t) of the first to N-th
transmitting radio frequency channels, where x.sub.n.sup.In(t)
represents the time domain signal of the N-th transmitting radio
frequency channel, and t represents the sequence number of a
temporal Orthogonal Frequency Division Multiplexing (OFDM)
signal.
[0167] Fifthly the formed time domain signals x.sub.1.sup.In(t),
x.sub.2.sup.In(t), x.sub.3.sup.In(t), . . . , x.sub.n.sup.In(t), .
. . , x.sub.N.sup.In(t) of the first to N-th transmitting radio
frequency channels are transmitted respectively over the
transmitting radio frequency channels in the first group. The
coupling network processes x.sub.1.sup.In(t), x.sub.2.sup.In(t),
x.sub.3.sup.In(t), . . . , x.sub.n.sup.In(t), . . . ,
x.sub.N.sup.In(t) into a compositive signal upon reception of
x.sub.1.sup.In(t), x.sub.2.sup.In(t), x.sub.3.sup.In(t), . . . ,
x.sub.n.sup.In(t), . . . , x.sub.N.sup.In(t), and transmits the
compositive signal to the calibration receiving channel to form
feedback signals y.sup.In(t) of the intra-group transmission
calibration pilot sequences corresponding to the first group of
transmitting radio frequency channels.
[0168] Sixthly the CP is removed from the received feedback signals
y.sup.In(t) of the intra-group transmission calibration pilot
sequences corresponding to the first group of transmitting radio
frequency channels, and Fast Fourier Transformation (FFT) is
performed on the feedback signals to form a received frequency
signal throughout the bandwidth. y.sup.In(t) can be processed by a
signal processor which may be located at the radio frequency side
or the baseband side in a physical entity.
[0169] Seventhly channel estimation is performed on the first group
of transmitting radio frequency channels according to the feedback
signals of the intra-group transmission calibration pilot sequences
received over the calibration receiving channel, and the
transmission calibration pilot sequences transmitted over the first
group of transmitting radio frequency channels to obtain channel
information of the corresponding sub-carriers, to which the
intra-group transmission calibration pilot sequences are mapped, in
the respective transmitting radio frequency channels in the first
group of transmitting radio frequency channels, where the channel
information of the corresponding sub-carriers of the intra-group
transmission calibration pilot sequences mapped in the respective
transmitting radio frequency channels in the first group of
transmitting radio frequency channels is determined in Equation (9)
of
H ~ n ( i ) = z In ( k ) s n In ( k ) ( 9 ) ##EQU00006##
[0170] In Equation (9) above:
[0171] k represents the index of each sub-carrier, and
k=i.DELTA.d.sub.sc.sup.In+.DELTA.f.sub.sc.sup.In(n-1); i represents
an index, i is a positive integer, 0.ltoreq.i<N.sub.sc.sup.In,
and N.sub.sc.sup.In, represents the length of an intra-group
transmission calibration pilot sequence; n represents the index of
each transmitting radio frequency channel in each group of
transmitting radio frequency channel, n is a positive integer, and
the value of n ranges from 1 to N; .DELTA.d.sub.sc.sup.In
represents the spacing between sub-carriers to which each
transmitting radio frequency channel is mapped, and
.DELTA.f.sub.sc.sup.In represents the spacing between sub-carriers
to which two adjacent transmitting radio frequency channels are
mapped.
[0172] z.sup.In(k) represents a frequency signal in the entire
bandwidth of a received feedback signal corresponding to an
intra-group transmission calibration pilot sequence corresponding
to the k-th sub-carrier of the first group of transmitting radio
frequency channels;
[0173] s.sub.n.sup.In(k) represents a transmission signal of the
k-th sub-carrier of the n-th transmitting radio frequency channel
in the first group of transmitting radio frequency channels;
and
[0174] {tilde over (H)}.sub.n(i) represents channel information of
a corresponding sub-carrier of the i-th intra-group transmission
calibration pilot sequence mapped in each transmitting radio
frequency channel in the first group of transmitting radio
frequency channels.
[0175] Eighthly in an implementation, channel estimation is
performed on each group of transmitting radio frequency channels
according to the feedback signals of the intra-group transmission
calibration pilot sequences received over the calibration receiving
channel, to obtain channel information corresponding to the
sub-carriers to which the intra-group transmission calibration
pilot sequences are mapped over each group of transmitting radio
frequency channels; and interpolation is performed according to the
channel information corresponding to the sub-carriers to which the
intra-group transmission calibration pilot sequences are mapped
over each group of transmitting radio frequency channels, to obtain
channel information corresponding to all the sub-carriers over each
group of transmitting radio frequency channels.
[0176] Particularly the channel information of the corresponding
sub-carriers, to which the intra-group transmission calibration
pilot sequences are mapped, in each transmitting radio frequency
channel in the first group of transmitting radio frequency channels
is calculated, and the indexes of the sub-carriers to which the
intra-group transmission calibration pilot sequences are mapped are
k=i.DELTA.d.sub.sc.sup.In+.DELTA.f.sub.sc.sup.In(n-1), where i
represents an index, i is a positive integer,
0.ltoreq.i<N.sub.sc.sup.In, and N.sub.sc.sup.In represents the
length of an intra-group transmission calibration pilot sequence; n
represents the index of each transmitting radio frequency channel
in each group of transmitting radio frequency channels, n is a
positive integer, and the value of n ranges from 1 to N;
.DELTA.d.sub.sc.sup.In represents the spacing between sub-carriers
to which each transmitting radio frequency channel is mapped, and
.DELTA.d.sub.sc.sup.In represents the spacing between sub-carriers
to which two adjacent transmitting radio frequency channels are
mapped.
[0177] As can be apparent, no corresponding channel estimation is
performed on a sub-carrier to which no intra-group transmission
calibration pilot sequence is mapped, so interpolation is performed
on all the other sub-carriers of all the transmitting radio
frequency channels in the first group of transmitting radio
frequency channels based upon the determined channel information of
the corresponding sub-carriers of the intra-group transmission
calibration pilot sequences mapped in the respective transmitting
radio frequency channels, to obtain the channel information of all
the sub-carriers throughout the operating bandwidth of all the
transmitting radio frequency channels in the first group of
transmitting radio frequency channels.
[0178] So far the channel information {tilde over (H)}.sub.n(k) of
all the sub-carriers throughout the operating bandwidth of all the
transmitting radio frequency channels in the first group of
transmitting radio frequency channels has been calculated in the
operations above. Alike intra-group transmission calibration pilot
sequences corresponding to the second group of transmitting radio
frequency channels are transmitted in a transmission timeslot
corresponding to the second group of transmitting radio frequency
channels, feedback signals thereof are received, and channel
information {tilde over (H)}.sub.N+n(k) of all the sub-carriers
throughout the operating bandwidth of all the transmitting radio
frequency channels in the second group of transmitting radio
frequency channels is further determined. Channel information
{tilde over (H)}.sub.(m-1).times.N+n(k) of all the sub-carriers
throughout the operating bandwidth of all the transmitting radio
frequency channels in the m-th group of transmitting radio
frequency channels is determined sequentially, where m represents
the number of a group including a transmitting radio frequency
channel, and the value of m ranges from 1 to M, until channel
information {tilde over (H)}.sub.(M-1).times.N+n(k) of all the
sub-carriers throughout the operating bandwidth of all the
transmitting radio frequency channels in the M-th group of
transmitting radio frequency channels is determined.
[0179] An inter-channel compensation coefficient of each
transmitting radio frequency channel is determined according to the
channel information of the M groups of transmitting radio frequency
channels.
[0180] In an implementation, the inter-channel compensation
coefficient of each transmitting radio frequency channel is
determined according to the channel information of each group of
transmitting radio frequency channels in a number of schemes in the
embodiments of the invention, several of which will be described
below without any limitation thereto.
[0181] In a first scheme, an inter-channel compensation coefficient
over each carrier of each transmitting radio frequency channel is
determined in Equation (10) of:
cal_factor q ( k ) = ( q = 1 MN H ~ q ( k ) 2 MN ) / H ~ q ( k ) (
10 ) ##EQU00007##
[0182] In Equation (10):
[0183] M represents the total number of groups of transmitting
radio frequency channels in the array of antennas;
[0184] N represents the total number of transmitting radio
frequency channels in each group of transmitting radio frequency
channels;
[0185] q=(m-1)N+n, where q represents the index of each
transmitting radio frequency channel, and q is a positive
integer;
[0186] {tilde over (H)}.sub.q(k) represents channel information of
the k-th sub-carrier of the n-th transmitting radio frequency
channel in the m-th group of transmitting radio frequency channels;
and
[0187] cal_factor.sub.q(k) represents an inter-channel compensation
coefficient of the k-th sub-carrier of the n-th transmitting radio
frequency channel in the m-th group of transmitting radio frequency
channels.
[0188] In a second scheme, an inter-channel compensation
coefficient over each carrier of each transmitting radio frequency
channel is determined in Equation (11) of:
cal_factor q ( k ) = q = 1 MN H ~ q ( k ) MN ( 11 )
##EQU00008##
[0189] In Equation (11):
[0190] M represents the total number of groups of transmitting
radio frequency channels in the array of antennas;
[0191] N represents the total number of transmitting radio
frequency channels in each group of transmitting radio frequency
channels;
[0192] q=(m-1)N+n, where q represents the index of each
transmitting radio frequency channel, and q is a positive
integer;
[0193] {tilde over (H)}.sub.q(k) represents channel information of
the k-th sub-carrier of the n-th transmitting radio frequency
channel in the m-th group of transmitting radio frequency channels;
and
[0194] cal_factor.sub.q(k) represents an inter-channel compensation
coefficient of the k-th sub-carrier of the n-th transmitting radio
frequency channel in the m-th group of transmitting radio frequency
channels.
[0195] In a third scheme, an inter-channel compensation coefficient
over each carrier of each transmitting radio frequency channel is
the minimum of the channel information of the k-th sub-carriers of
all the transmitting radio frequency channels.
[0196] In an implementation, a Field Programmable Gate Array (FPGA)
interface is filled with the inter-channel compensation
coefficients over the respective carriers of the respective
transmitting radio frequency channels, both information about
active transmitting radio frequency channels, and information about
inactive transmitting radio frequency channels is written into the
FPGA interface, and the information about the respective channels
is transmitted to a BBU.
[0197] In an implementation, an embodiment of the invention further
provides another implementation in which an inter-channel
compensation coefficient of each transmitting radio frequency
channel is determined in connection with a reference channel as
described below in details.
[0198] FIG. 5 illustrates a schematic flow chart of another method
for calibrating an antenna according to an embodiment of the
invention, and as illustrated in FIG. 5, the method particularly
includes the following operations:
[0199] The operation 501 is substantially the same as the flow
performed in the operation 101 in the embodiments above;
[0200] The operation 502 is substantially the same as the flow
performed in the operation 102 in the embodiments above;
[0201] The operation 503 is to select a reference channel from each
group of transmitting radio frequency channels respectively
according to the channel information of each group of transmitting
radio frequency channels to obtain M reference channels; to
transmit inter-group transmission calibration pilot sequences over
the M reference channels, and to perform channel estimation on the
M reference channels according to feedback signals of the
inter-group transmission calibration pilot sequences received over
a calibration receiving channel to obtain channel information of
the M reference channels; and to revise the channel information of
the group of transmitting radio frequency channels corresponding to
each reference channel respectively according to the channel
information of each reference channel; and
[0202] The operation 504 is to determine the inter-channel
compensation coefficient of each transmitting radio frequency
channel according to the revised channel information of each group
of transmitting radio frequency channels.
[0203] Particularly one of transmitting radio frequency channels in
each group of transmitting radio frequency channels is selected as
a reference channel of the group, so that M reference channels can
be determined from the M groups of transmitting radio frequency
channels. Channel estimation is performed on the M reference
channels using inter-group transmission calibration pilot
sequences. In an implementation, each reference channel may
correspond respectively to an inter-group transmission calibration
pilot sequence, and different reference channels may correspond to
different inter-group transmission calibration pilot sequences; or
the M reference channels may correspond to the same inter-group
transmission calibration pilot sequence. The inter-group
transmission calibration pilot sequences can be determined as
described above.
[0204] In an implementation, a reference channel is selected from
each group of transmitting radio frequency channels respectively
according to the channel information of each group of transmitting
radio frequency channels particularly as follows:
[0205] For each group of transmitting radio frequency channels, the
following operations are performed:
[0206] Receive power of each transmitting radio frequency channel
in the group of transmitting radio frequency channels is
determined; and
[0207] Transmitting radio frequency channels with their receive
power being not below a first threshold as active transmitting
radio frequency channels, and a reference channel is selected from
all the active transmitting radio frequency channels in the group
of transmitting radio frequency channels according to the receive
power of all the active transmitting radio frequency channels in
the group of transmitting radio frequency channels.
[0208] The following description will be made in details taking
particularly the first group of transmitting radio frequency
channels as an example. Firstly receive power of each transmitting
radio frequency channel in the first group of transmitting radio
frequency channels is determined according to channel information
of each transmitting radio frequency channel in the first group of
transmitting radio frequency channels in Equation (12) of:
P n = k = 0 N RB N sc RB - 1 H ~ q ( k ) 2 ( 12 ) ##EQU00009##
[0209] In Equation (12):
[0210] k represents the index of each sub-carrier;
[0211] N.sub.RB represents the number of resource blocks in a
system operating bandwidth of a single transmitting radio frequency
channel, and N.sub.sc.sup.RB represents the number of sub-carriers
in each resource block;
[0212] P.sub.n represents receive power of the n-th transmitting
radio frequency channel in the first group of transmitting radio
frequency channels; and
[0213] {tilde over (H)}.sub.n(k) represents channel information of
the k-th sub-carrier of the n-th transmitting radio frequency
channel in the first group of transmitting radio frequency
channels.
[0214] In an implementation, a first threshold is determined, and
if receive power of some channel is below the first threshold, then
the channel will be determined as an inactive transmitting radio
frequency channel; otherwise, the transmitting radio frequency
channel with the receive power being not below the first threshold
will be determined as an active transmitting radio frequency
channel. The antenna channel may become inactive due to a failure
thereof or another factor, so the inactive transmitting radio
frequency channel may be discarded for being selected as a
reference channel.
[0215] Particularly a reference channel can be selected from all
the active transmitting radio frequency channels in the group of
transmitting radio frequency channels according to the receive
power of all the active transmitting radio frequency channels in
the group of transmitting radio frequency channels in a number of
schemes, and two common schemes thereof will be described
below.
[0216] In a first scheme, the average of the receive power of all
the active transmitting radio frequency channels in the group can
be calculated, the receive power of the active channels more than
the average of the receive power in the first group of transmitting
radio frequency channels can be sorted, and a channel with the
closest receive power to the average power can be selected from the
active transmitting radio frequency channels with their receive
power more than the average of the receive power as a reference
channel n.sup.Ref(1) of the first group of transmitting radio
frequency channels.
[0217] In a second scheme, a channel with the highest receive power
in the first group of transmitting radio frequency channels can be
selected as a reference channel n.sup.Ref(1) of the first group of
transmitting radio frequency channels.
[0218] Alike a reference channel n.sup.Ref(2) of the second group
of transmitting radio frequency channels is determined according to
the channel information {tilde over (H)}.sub.N+n(k) of each
transmitting radio frequency channel in the second group of
transmitting radio frequency channels; a reference channel
n.sup.Ref(m) of the m-th group of transmitting radio frequency)
channels is determined according to the channel information {tilde
over (H)}.sub.(m-1).times.N+n(k) of each transmitting radio
frequency channel in the m-th group of transmitting radio frequency
channels; . . . ; and a reference channel n.sup.Ref(M) of the M-th
group of transmitting radio frequency channels is determined
according to the channel information {tilde over
(H)}.sub.M.times.N+n(k) of each transmitting radio frequency
channel in the M-th group of transmitting radio frequency
channels.
[0219] As can be apparent, the reference channels n.sup.Ref(m) of
the respective groups of transmitting radio frequency channels are
determined respectively as described above, where m represents the
sequence number of each group of transmitting radio frequency
channels, m is a positive integer, and the value of m ranges from 1
to M.
[0220] In an implementation, information about the active
transmitting radio frequency channels in each group of transmitting
radio frequency channels is stored, and subsequently can be
transmitted to a Building Baseband Unit (BBU) for processing by the
BBU. For example, if the BBU knows that some transmitting radio
frequency channel is an inactive transmitting radio frequency
channel, then the BBU subsequently transmitting a signal may
discard the inactive transmitting radio frequency channel, may
report of the failure, etc.
[0221] Channel estimation on a reference channel will be described
below in details.
[0222] Firstly the inter-group transmission calibration pilot
sequences of the determined reference channels of the respective
groups of transmitting radio frequency channels are determined as
described above.
[0223] Secondly a pattern in which the inter-group transmission
calibration pilot sequences corresponding to the reference channels
are mapped in the reference channels is determined. Since the total
number M of reference channels is less than the total number of all
the antennas in the array of antennas at a large scale, the
inter-group transmission calibration pilot sequences can be mapped
in the reference channels in a number of patterns.
[0224] In a first pattern, the inter-group transmission calibration
pilot sequences are transmitted over the M reference channels in a
transmission timeslot of the inter-group transmission calibration
pilot sequences in the current calibration period, where the
inter-group transmission calibration pilot sequences are
transmitted over different frequency resources of the M reference
channels.
[0225] Particularly if the inter-group transmission calibration
pilot sequences mapped onto the group of reference channels are
transmitted in a transmission timeslot, then the inter-group
transmission calibration pilot sequences will be mapped onto
different frequency resources corresponding to the respective
reference channels in the frequency division mode.
[0226] In an implementation, as illustrated in FIG. 3, the
inter-group transmission calibration pilot sequences mapped onto
the reference channels are transmitted in the fourth transmission
timeslot 309, where the time interval between the inter-group
transmission calibration pilot sequences mapped onto the reference
channels, and the intra-group transmission calibration pilot
sequences mapped onto the M-th group of transmitting radio
frequency channels is a reference channel calibration offset 310,
i.e., .DELTA.T.sup.Ref; and if the interval between transmission
timeslots of every two adjacent groups of transmitting radio
frequency channels is an inter-group transmission calibration
offset 302, i.e., .DELTA.T.sup.In, then the period of time from the
time when the intra-group transmission calibration pilot sequences
start to be transmitted over the first group of transmitting radio
frequency channels, to the time when the inter-group transmission
calibration pilot sequences are transmitted over the reference
channels will be a transmission calibration offset 311, i.e.,
.DELTA.T, where .DELTA.T=(M-1).DELTA.T.sup.In+.DELTA.T.sup.Ref. In
an implementation, the transmission timeslots are guard
timeslots.
[0227] In a second pattern, the inter-group transmission
calibration pilot sequences mapped onto the respective reference
channels are transmitted respectively in different timeslots in the
time division mode to perform channel estimation on the respective
reference channels. At this time, the inter-group transmission
calibration pilot sequences can be mapped onto any frequency
resources of the respective reference channels.
[0228] In a third pattern, channel estimation is performed on the
respective reference channels in the code division mode.
[0229] For the sake of a convenient description, the frequency
division mode in the first implementation will be described below
in an embodiment of the invention, but channel estimation on the
reference channels will not be limited thereto. In an embodiment of
the invention, the reference channels are regarded as a group, and
the inter-group transmission calibration pilot sequences
corresponding to the reference channels are transmitted in a
transmission timeslot.
[0230] The inter-group transmission calibration pilot sequences may
be mapped onto different frequency resources corresponding to each
reference channel in a number of patterns. In an implementation,
the inter-group transmission calibration pilot sequences are mapped
onto the sub-carriers in the entire operating bandwidth of each
reference channel, where the spacing between sub-carriers to which
each reference channel is mapped is a first sub-carrier offset more
than or equal to M, and the spacing between sub-carriers to which
two adjacent reference channels are mapped is a second sub-carrier
offset less than the first sub-carrier offset. The inter-group
transmission calibration pilot sequences are mapped onto different
frequency resources corresponding to each reference channel in a
pattern similar to the pattern in which the intra-group
transmission calibration pilot sequences are mapped onto different
frequency resources corresponding to each transmitting radio
frequency channel in each group of transmitting radio frequency
channels.
[0231] In an implementation, the spacing between sub-carriers to
which each reference channel is mapped, and the spacing between
sub-carriers to which two adjacent reference channels are mapped
are determined as describe above, and the inter-group transmission
calibration pilot sequences corresponding to the reference channels
are mapped into the respective reference channels at the spacing
between sub-carriers to which each reference channel is mapped, and
the spacing between sub-carriers to which two adjacent reference
channels are mapped. The spacing between sub-carriers to which two
adjacent reference channels are mapped is determined in Equation
(13) of:
.DELTA. f sc Ref = .DELTA. d sc Ref M ( 13 ) ##EQU00010##
[0232] In Equation (13) above:
[0233] .DELTA.d.sub.sc.sup.Ref represents the spacing between
sub-carriers to which each reference channel is mapped;
[0234] M represents the total number of transmitting radio
frequency channels;
[0235] .left brkt-bot..cndot..right brkt-bot. represents rounding
down; and
[0236] .DELTA.f.sub.sc.sup.Ref represents the spacing between
sub-carriers to which two adjacent reference channels are
mapped.
[0237] Particularly as illustrated in FIG. 6, FIG. 6 illustrates a
schematic diagram of mapping inter-group transmission calibration
pilot sequences onto sub-carriers in the entire operating bandwidth
of reference channels according to an embodiment of the invention.
As illustrated, there is a schematic diagram of reference channels,
where there are five groups of reference channels in total in the
array of antennas, that is, M is 5, and since each group of
reference channels corresponds to a reference channel, there are
five reference channels in total in the array of antennas, which
are a first reference channel 601, a second reference channel 602,
a third reference channel 603, a fourth reference channel 604, and
a fifth reference channel 605 respectively, and each reference
channel corresponds to an operating bandwidth 609 including all the
sub-carriers in the corresponding reference channel.
[0238] The spacing between sub-carriers to which each reference
channel is mapped is a first sub-carrier offset 610. Particularly
in FIG. 6, the spacing between a first inter-group transmission
calibration pilot sequence 606 and a second inter-group
transmission calibration pilot sequence 607 mapped in the first
reference channel 601 is the first sub-carrier offset 610. The
spacing between sub-carriers to which two adjacent reference
channels are mapped is a second sub-carrier offset 611.
Particularly in FIG. 6, the spacing between the first inter-group
transmission calibration pilot sequence 606 in the first reference
channel 601, and the first inter-group transmission calibration
pilot sequence 606 in the second reference channel 602 is the
second sub-carrier offset 611.
[0239] The inter-group transmission calibration pilot sequences
corresponding to each reference channel are determined as described
above as c.sup.Ref(0), c.sup.Ref(1), c.sup.Ref(2), . . .
c.sup.Ref(j) . . . c.sup.Ref(N.sub.sc.sup.Ref-1) respectively,
where C.sup.Ref(j) represents the j-th inter-group transmission
calibration pilot sequence corresponding to the reference channel,
j represents an index, 0.ltoreq.j<N.sub.sc.sup.Ref and
N.sub.sc.sup.Ref j represents the length of an inter-group
transmission calibration pilot sequence. All the inter-group
transmission calibration pilot sequences are mapped respectively
into each reference channel. As illustrated in FIG. 6, firstly
c.sup.Ref(0) i.e., the first inter-group transmission calibration
pilot sequence 606, is mapped into each reference channel, next
c.sup.Ref(1), i.e., the second inter-group transmission calibration
pilot sequence 607, is mapped into each reference channel, and the
inter-group transmission calibration pilot sequences determined are
mapped respectively into each reference channel sequentially, until
lastly c.sup.Ref(N.sub.sc.sup.Ref-1) i.e., the
(N.sub.sc.sup.Ref-1)-th inter-group transmission calibration pilot
sequence 608, is mapped into each reference channel.
[0240] As can be apparent from FIG. 6, if the inter-group
transmission calibration pilot sequences corresponding respectively
to each group of reference channels are mapped onto the
sub-carriers in the entire operating bandwidth of the reference
channels in the frequency division mode, then the distance denoted
by the first sub-carrier offset 610 in FIG. 6 may be the spacing
.DELTA.d.sub.sc.sup.Ref between sub-carriers to which each
transmitting radio frequency channel is mapped. Since inter-group
transmission calibration pilot sequences need to be mapped onto
different frequency resources in each reference channel in the
group of reference channels within the first sub-carrier offset
610, .DELTA.d.sub.sc.sup.Ref.gtoreq.5 shall be satisfied in FIG. 6
so that there is an inter-group transmission calibration pilot
sequence mapped onto each of five reference channels within each
first sub-carrier offset 610 among the reference channels in FIG.
6, and the respective inter-group transmission calibration pilot
sequences are mapped onto different frequency resources.
[0241] In an implementation, if the first sub-carrier offset 610 is
set larger, then the inter-group transmission calibration pilot
sequences mapped into the respective reference channels may be
arranged uniformly in the first sub-carrier offset 610. For
example, the second sub-carrier offset 611 illustrated in FIG. 6 is
the spacing of one sub-carrier. In an implementation, the second
sub-carrier offset 611 may alternatively be the spacing of more
than one sub-carrier, but the embodiments of the invention will not
be limited to any particular spacing. The second sub-carrier offset
611 in FIG. 6 is the spacing between sub-carriers to which two
adjacent transmitting radio frequency channels are mapped.
[0242] Thirdly the inter-group transmission calibration pilot
sequences corresponding to the reference channels are mapped into
each reference channel, and transmission signals of the M reference
channels are generated, where the transmission signals of the M
reference channels are generated in Equation (14) of:
s.sub.m.sup.Ref(k)=c.sup.Ref(j) (14)
[0243] In Equation (14) above:
[0244] j represents an index, 0.ltoreq.j<N.sub.sc.sup.Ref, and
N.sub.sc.sup.Ref represents the length of an inter-group
transmission calibration pilot sequence;
[0245] c.sup.Ref(j) represents the j-th inter-group transmission
calibration pilot sequence corresponding to the reference
channel;
[0246] m represents the sequence number of the group including a
transmitting radio frequency channel which is the reference
channel, m is a positive integer, and the value of m ranges from 1
to M;
[0247] k represents the index of each sub-carrier,
k=j.DELTA.d.sub.sc.sup.Ref+.DELTA.f.sub.sc.sup.Ref (m-1), and the
value of k ranges from 0 to N.sub.RBN.sub.sc.sup.RB-1, where
N.sub.RB represents the number of resource blocks in a system
operating bandwidth of a single transmitting radio frequency
channel, and N.sub.sc.sup.RB represents the number of sub-carriers
in each resource block; .DELTA.d.sub.sc.sup.Ref represents the
spacing between sub-carriers to which each reference channel is
mapped, and .DELTA.f.sub.sc.sup.In represents the spacing between
sub-carriers to which two adjacent reference channels are mapped;
and
[0248] s.sub.m.sup.Ref(k) represents a transmission signal of the
k-th sub-carrier of a reference channel corresponding to the m-th
group of transmitting radio frequency channels.
[0249] Particularly the transmission signals of the M transmitting
radio frequency channels can be generated by a signal processor
which may be located at the radio frequency side or the baseband
side in a physical entity. Particularly since the reference
channels include M transmitting radio frequency channels, the
series of transmission signals of the M transmitting radio
frequency channels can be written as s.sub.1.sup.Ref(k),
s.sub.2.sup.Ref(k), s.sub.3.sup.Ref(k), . . . ,
s.sub.M.sup.Ref(k).
[0250] Fourthly in the first to M-th reference channels in the
reference channels, IFFT is performed respectively on
s.sub.1.sup.Ref(k), s.sub.2.sup.Ref(k), s.sub.3.sup.Ref(k), . . . ,
s.sub.M.sup.Ref(k), and a corresponding CP is added thereto to form
time domain signals x.sub.1.sup.Ref(t), x.sub.2.sup.Ref(t),
x.sub.3.sup.Ref(t), . . . x.sub.m.sup.Ref(t), . . . ,
x.sub.M.sup.Ref(t) of the first to M-th reference channels, where
x.sub.m.sup.Ref(t) represents the time domain signal of the m-th
reference channel, and t represents the sequence number of a
temporal OFDM symbol.
[0251] Fifthly the formed time domain signals x.sub.1.sup.Ref(t),
x.sub.2.sup.Ref(t), x.sub.3.sup.Ref(t), . . . x.sub.m.sup.Ref(t), .
. . , x.sub.M.sup.Ref(t) of the first to M-th reference channels
are transmitted respectively over the reference channels.
[0252] The coupling network processes x.sub.1.sup.Ref(t),
x.sub.2.sup.Ref(t), x.sub.3.sup.Ref(t), . . . x.sub.m.sup.Ref(t), .
. . , x.sub.M.sup.Ref(t) into a compositive signal upon reception
of x.sub.1.sup.Ref(t), x.sub.2.sup.Ref(t), x.sub.3.sup.Ref(t), . .
. x.sub.m.sup.Ref(t), . . . , x.sub.M.sup.Ref(t), and transmits the
compositive signal to the calibration receiving channel to form
feedback signals y.sup.Ref(t) of the inter-group transmission
calibration pilot sequences corresponding to the reference
channels.
[0253] Sixthly the CP is removed from the received feedback signals
y.sup.Ref(t) of the inter-group transmission calibration pilot
sequences corresponding to the reference channels, and FFT is
performed on the feedback signals to form a received frequency
signal throughout the bandwidth. y.sup.Ref(t) can be processed by a
signal processor which may be located at the radio frequency side
or the baseband side in a physical entity.
[0254] Seventhly channel estimation is performed on the reference
channels according to the frequency signal in the entire bandwidth
of the feedback signals of the inter-group transmission calibration
pilot sequences received over the calibration receiving channel,
and the transmission signals of the reference channels
corresponding to the transmitting radio frequency channels
transmitted over the reference channels to obtain channel
information of the corresponding sub-carriers, to which the
inter-group transmission calibration pilot sequences are mapped, in
the respective transmitting radio frequency channels in the
reference channels, where the channel information of the
corresponding sub-carriers of the inter-group transmission
calibration pilot sequences mapped in the reference channels
corresponding to each group of transmitting radio frequency
channels is determined in Equation (15) of:
H ~ m Ref ( j ) = z Ref ( k ) s m Ref ( k ) ( 15 ) ##EQU00011##
[0255] In Equation (15) above:
[0256] k represents the index of each sub-carrier,
k=j.DELTA.d.sub.sc.sup.Ref+.DELTA.f.sub.sc.sup.Ref (m-1) and the
value of k ranges from 0 to N.sub.RBN.sub.sc.sup.RB-1, where
N.sub.RB represents the number of resource blocks in a system
operating bandwidth of a single transmitting radio frequency
channel, and N.sub.sc.sup.RB represents the number of sub-carriers
in each resource block; j represents an index,
0.ltoreq.j<N.sub.sc.sup.Ref, N.sub.sc.sup.Ref represents the
length of an inter-group transmission calibration pilot sequence, m
represents the number of the group including a transmitting radio
frequency channel which is the reference channel, m is a positive
integer, and the value of m ranges from 1 to M;
.DELTA.d.sub.sc.sup.Ref represents the spacing between sub-carriers
to which each reference channel is mapped; and
.DELTA.f.sub.sc.sup.Ref represents the spacing between sub-carriers
to which two adjacent reference channels are mapped.
[0257] s.sub.m.sup.Ref(k) represents a transmission signal of the
k-th sub-carrier of the reference channel corresponding to the m-th
group of transmitting radio frequency channels;
[0258] z.sup.Ref(k) represents a frequency signal in the entire
bandwidth of a received feedback signal corresponding to an
inter-group transmission calibration pilot sequence corresponding
to the k-th sub-carrier of the reference channel; and
[0259] {tilde over (H)}.sub.m.sup.Ref(j) represents channel
information of a corresponding sub-carrier of the j-th inter-group
transmission calibration pilot sequence mapped in the reference
channel corresponding to the m-th group of transmitting radio
frequency channels.
[0260] Eighthly in an implementation, channel estimation is
performed on the M reference channels according to the feedback
signals of the inter-group transmission calibration pilot sequences
received over the calibration receiving channel particularly as
follows:
[0261] Channel estimation is performed on the M reference channels
according to the feedback signals of the inter-group transmission
calibration pilot sequences received over the calibration receiving
channel, to obtain channel information corresponding to the
sub-carriers to which the inter-group transmission calibration
pilot sequences are mapped over each reference channel; and
interpolation is performed according to the channel information
corresponding to the sub-carriers to which the inter-group
transmission calibration pilot sequences are mapped over each
reference channel, to obtain channel information corresponding to
all the sub-carriers over each reference channel.
[0262] Particularly the channel information of the corresponding
sub-carriers, to which the inter-group transmission calibration
pilot sequences are mapped, in the reference channels is
calculated, and the indexes of the sub-carriers are
k=j.DELTA.d.sub.sc.sup.Ref+.DELTA.f.sub.sc.sup.Ref(m-1), where j
represents an index, 0.ltoreq.j<N.sub.sc.sup.Ref, and
N.sub.sc.sup.Ref represents the length of an inter-group
transmission calibration pilot sequence; m represents the number of
a group including a transmitting radio frequency channel which is a
reference channel, m is a positive integer, and the value of m
ranges from 1 to M; the value of k ranges from 0 to
N.sub.RBN.sub.sc.sup.RB-1, where N represents the number of
resource blocks in a system operating bandwidth of a single
transmitting radio frequency channel, and N.sub.sc.sup.RB
represents the number of sub-carriers in each resource block;
.DELTA.d.sub.sc.sup.Ref represents the spacing between sub-carriers
to which each reference channel is mapped; and
.DELTA.f.sub.sc.sup.Ref represents the spacing between sub-carriers
to which two adjacent reference channels are mapped. As can be
apparent, no corresponding channel estimation is performed on a
sub-carrier to which no inter-group transmission calibration pilot
sequence is mapped, so interpolation is performed on all the other
sub-carriers in the reference channels based upon the determined
channel information of the corresponding sub-carriers of the
inter-group transmission calibration pilot sequences mapped in the
reference channels corresponding to the respective groups of
transmitting radio frequency channels, to obtain the channel
information of all the sub-carriers throughout the operating
bandwidth of the reference channels.
[0263] So far the channel information of all the sub-carriers
throughout the operating bandwidth of the reference channels has
been calculated in the operations above. Alike
[0264] In an implementation, channel information of a group of
transmitting radio frequency channels corresponding to each
reference channel can be revised respectively according to channel
information of each reference channel, and particularly for each
group of transmitting radio frequency channels:
[0265] The ratio of channel information obtained based upon the
inter-group transmission calibration pilot sequences, to channel
information based upon the intra-group transmission calibration
pilot sequences, of the reference channel of the group of
transmitting radio frequency channels as a revision coefficient
corresponding to the group of transmitting radio frequency
channels; and
[0266] The product of the revision coefficient corresponding to the
group of transmitting radio frequency channels, and the channel
information of each transmitting radio frequency channel in the
group of transmitting radio frequency channels obtained based upon
the intra-group transmission calibration pilot sequences as revised
channel information of each transmitting radio frequency channel in
the group of transmitting radio frequency channels.
[0267] Particularly the index of a reference channel of each group
of transmitting radio frequency channels among all the transmitting
radio frequency channels is determined as
q.sup.Ref(m)=(m-1)N+n.sup.Ref(m) according to the channel
information of all the sub-carriers in the entire operating
bandwidth of the M reference channels, where n.sup.Ref(m)
represents the index of a reference channel of the m-th group of
transmitting radio frequency channels among the transmitting radio
frequency channels in the original group, and the value of
n.sup.Ref(m) ranges from 1 to N.
[0268] Accordingly the revision coefficient of each group of
transmitting radio frequency channels is calculated according to
the channel information of the reference channel of each group of
transmitting radio frequency channels obtained based upon the
inter-group transmission calibration pilot sequences, and the
channel information of the reference channel of each group of
transmitting radio frequency channels obtained based upon the
intra-group transmission calibration pilot sequences in Equation
(16) of:
F m ( k ) = H ~ m Ref ( k ) H ~ q Ref ( m ) ( k ) ( 16 )
##EQU00012##
[0269] In Equation (16) above:
[0270] k represents the index of each sub-carrier, and the value of
k ranges from 0 to N.sub.RBN.sub.sc.sup.RB-1, where N.sub.RB
represents the number of resource blocks in a system operating
bandwidth of a single transmitting radio frequency channel, and
N.sub.sc.sup.RB represents the number of sub-carriers in each
resource block;
[0271] {tilde over (H)}.sub.m.sup.Ref(k) represents channel
information of the k-th sub-carrier of the reference channel of the
m-th group of transmitting radio frequency channels based upon the
inter-group transmission calibration pilot sequence;
[0272] {tilde over (H)}.sub.q.sub.Ref.sub.(m)(k) represents channel
information of the k-th sub-carrier of the reference channel of the
m-th group of transmitting radio frequency channels based upon the
intra-group transmission calibration pilot sequence; and
[0273] F.sub.m(k) represents a revision coefficient of the k-th
sub-carrier of the m-th group of transmitting radio frequency
channels.
[0274] Next channel information of each sub-carrier in each
transmitting radio frequency channel in each group of transmitting
radio frequency channels is revised using the revision coefficient
of each group of transmitting radio frequency channels in Equation
(17) of:
{tilde over (H)}.sub.(m-1)N+n.sup.modify(k)=F.sub.m(k){tilde over
(H)}.sub.(m-1)N+n(k) (17)
[0275] In Equation (17) above:
[0276] F.sub.m(k) represents a revision coefficient of the k-th
sub-carrier of the m-th group of transmitting radio frequency
channels;
[0277] {tilde over (H)}.sub.(m-1)N+n(k) represents channel
information of the k-th sub-carrier of the n-th transmitting radio
frequency channel in the m-th group of transmitting radio frequency
channels; and
[0278] {tilde over (H)}.sub.(m-1)N+n.sup.modify(k) represents
revised channel information of k-th sub-carrier of the n-th
transmitting radio frequency channel in the m-th group of
transmitting radio frequency channels.
[0279] In an implementation, an inter-channel compensation
coefficient of each transmitting radio frequency channel can be
determined according to the revised channel information of each
group of transmitting radio frequency channels in a number of
schemes in the embodiments of the invention, several of which will
be described below without any limitation thereto.
[0280] In a first scheme, an inter-channel compensation coefficient
over each carrier of each transmitting radio frequency channel is
determined in Equation (18) of:
cal_factor q ( k ) = ( q = 1 MN H ~ q modify ( k ) 2 MN ) / H ~ q
modify ( k ) ( 18 ) ##EQU00013##
[0281] In Equation (18) above:
[0282] M represents the total number of groups of transmitting
radio frequency channels in the array of antennas;
[0283] N represents the total number of transmitting radio
frequency channels in each group of transmitting radio frequency
channels;
[0284] q=(m-1)N+n, where q represents the index of each
transmitting radio frequency channel, and q is a positive
integer;
[0285] {tilde over (H)}.sub.q.sup.modify(k) represents revised
channel information of the k-th sub-carrier of the n-th
transmitting radio frequency channel in the m-th group of
transmitting radio frequency channels; and
[0286] cal_factor.sub.q(k) represents an inter-channel compensation
coefficient of the k-th sub-carrier of the n-th transmitting radio
frequency channel in the m-th group of transmitting radio frequency
channels.
[0287] In a second scheme, an inter-channel compensation
coefficient over each carrier of each transmitting radio frequency
channel is determined in Equation (19) of:
cal_factor q ( k ) = q = 1 MN H ~ q modify ( k ) MN ( 19 )
##EQU00014##
[0288] In Equation (19) above:
[0289] M represents the total number of groups of transmitting
radio frequency channels in the array of antennas;
[0290] N represents the total number of transmitting radio
frequency channels in each group of transmitting radio frequency
channels;
[0291] q=(m-1)N+n, where q represents the index of each
transmitting radio frequency channel, and q is a positive
integer;
[0292] {tilde over (H)}.sub.q.sup.modify(k) represents revised
channel information of the k-th sub-carrier of the n-th
transmitting radio frequency channel in the m-th group of
transmitting radio frequency channels; and
[0293] cal_factor.sub.q(k) represents an inter-channel compensation
coefficient of the k-th sub-carrier of the n-th transmitting radio
frequency channel in the m-th group of transmitting radio frequency
channels.
[0294] In a third scheme, an inter-channel compensation coefficient
over each carrier of each transmitting radio frequency channel is
the minimum of the revised channel information of the k-th
sub-carriers of all the transmitting radio frequency channels.
[0295] In an implementation, an FPGA interface is filled with the
inter-channel compensation coefficients cal_factor.sub.q(k) over
the respective carriers of the respective transmitting radio
frequency channels, both information about active transmitting
radio frequency channels, and information about inactive
transmitting radio frequency channels is written into the FPGA
interface, and the information about the respective channels is
transmitted to a BBU.
[0296] As can be apparent from the description above, in an
implementation, Q transmitting radio frequency channels are grouped
into M groups, and intra-group transmission calibration pilot
sequences are mapped onto different resources in the respective
groups of transmission radio frequency channels in the FDM mode, in
the embodiments of the invention. The different groups of
intra-group transmission calibration pilot sequences are
transmitted in different transmission timeslots in the Time
Division Multiplexing (TDM) mode among the M groups of intra-group
transmission calibration pilot sequences.
[0297] As can be apparent from the disclosure above, the
transmitting radio frequency channels in the array of antenna are
grouped into M groups, and the intra-group transmission calibration
pilot sequences of the corresponding groups are transmitted
respectively in the transmission timeslots corresponding
respectively to the respective groups of transmitting radio
frequency channels, where the transmission timeslots of the
intra-group transmission calibration pilot sequences corresponding
to the different groups are different from each other, that is, for
the M groups transmitting radio frequency channels, the intra-group
transmission calibration pilot sequences of the respective groups
of transmitting radio frequency channels are transmitted in the
different transmission timeslots in the time division mode, so
channel estimation can be performed separately on each group of
transmitting radio frequency channels, and if channel estimation is
performed on each group of transmitting radio frequency channels in
the frequency division mode, then simply the intra-group
transmission calibration pilot sequences will be transmitted over
different frequency resources in respective transmitting radio
frequency channels in a group, that is, for each group of
transmitting radio frequency channels, intra-group transmission
calibration pilot sequences corresponding to each group can be
mapped into the group of transmitting radio frequency channels in
the frequency division mode, so there are such a smaller number of
transmitting radio frequency channels in each group that longer
intra-group transmission calibration pilot sequences can be mapped
onto the respective radio frequency channels in the group in the
frequency division mode; and furthermore there is an increase in
the length of the intra-group transmission calibration pilot
sequences for channel estimation mapped onto the respective radio
frequency channels, the precision of the determined inter-channel
compensation coefficients of the respective transmitting radio
frequency channels can be improved.
[0298] FIG. 7 illustrates a schematic structural diagram of an
apparatus for calibrating an antenna.
[0299] Based upon the same idea, an embodiment of the invention
provides an apparatus for calibrating an antenna as illustrated in
FIG. 7, which includes an obtaining unit 701, a first processing
unit 702, and a first determining unit 703, where the first
determining unit 703 further includes a selecting unit 704, a
second processing unit 705, and a second determining unit 706;
[0300] The obtaining unit 701 is configured to obtain information
about grouping of transmitting radio frequency channels, where the
transmitting radio frequency channels in an array of antennas are
grouped into M groups, and M is an integer more than 1;
[0301] The first processing unit 702 is configured to transmit
intra-group transmission calibration pilot sequences corresponding
respectively to the respective groups of transmitting radio
frequency channels over the corresponding groups of transmitting
radio frequency channels respectively in transmission timeslots of
the intra-group transmission calibration pilot sequences, and to
perform channel estimation on the respective groups of transmitting
radio frequency channels according to feedback signals of the
intra-group transmission calibration pilot sequences received over
a calibration receiving channel to obtain channel information of
the M groups of transmitting radio frequency channels, where there
are different transmission timeslots of intra-group transmission
calibration pilot sequences corresponding to different groups;
and
[0302] The first determining unit 703 is configured to determine
inter-channel compensation coefficients of the respective
transmitting radio frequency channels according to the channel
information of the M groups of transmitting radio frequency
channels.
[0303] In an implementation, each group of transmitting radio
frequency channels includes N transmitting radio frequency
channels, where N is 1, or N is an integer more than 1. If N is an
integer more than 1, then intra-group transmission calibration
pilot sequences will be transmitted over different frequency
resources in respective transmitting radio frequency channels in a
group.
[0304] In an implementation, the first determining unit 703
includes:
[0305] The selecting unit 704 is configured to select a reference
channel from each group of transmitting radio frequency channels
respectively according to the channel information of each group of
transmitting radio frequency channels to obtain M reference
channels;
[0306] The second processing unit 705 is configured to transmit
inter-group transmission calibration pilot sequences over the M
reference channels, and to perform channel estimation on the M
reference channels according to feedback signals of the inter-group
transmission calibration pilot sequences received over the
calibration receiving channel to obtain channel information of the
M reference channels; and
[0307] The second determining unit 706 is configured to revise the
channel information of the group of transmitting radio frequency
channels corresponding to each reference channel respectively
according to the channel information of each reference channel; and
to determine the inter-channel compensation coefficient of each
transmitting radio frequency channel according to the revised
channel information of each group of transmitting radio frequency
channels.
[0308] In an implementation, the selecting unit 704 is
configured:
[0309] For each group of transmitting radio frequency channels,
[0310] To determine receive power of each transmitting radio
frequency channel in the group of transmitting radio frequency
channels; and
[0311] To determine transmitting radio frequency channels with
their receive power being not below a first threshold as active
transmitting radio frequency channels, and to select a reference
channel from all the active transmitting radio frequency channels
in the group of transmitting radio frequency channels according to
the receive power of all the active transmitting radio frequency
channels in the group of transmitting radio frequency channels.
[0312] The second processing unit 705 is configured:
[0313] To map the inter-group transmission calibration pilot
sequences onto the sub-carriers in the entire operating bandwidth
of each reference channel, where the spacing between sub-carriers
to which each reference channel is mapped is a first sub-carrier
offset more than or equal to M, and the spacing between
sub-carriers to which two adjacent reference channels are mapped is
a second sub-carrier offset less than the first sub-carrier
offset.
[0314] In an implementation, the second processing unit 705 is
configured:
[0315] To transmit the inter-group transmission calibration pilot
sequences over the M reference channels in a transmission timeslot
of the inter-group transmission calibration pilot sequences in the
current calibration period, where the inter-group transmission
calibration pilot sequences are transmitted over different
frequency resources of the M reference channels.
[0316] In an implementation, the second processing unit 705 is
configured:
[0317] To perform channel estimation on the M reference channels
according to the feedback signals of the inter-group transmission
calibration pilot sequences received over the calibration receiving
channel, to obtain channel information corresponding to the
sub-carriers to which the inter-group transmission calibration
pilot sequences are mapped over each reference channel; and
[0318] To perform interpolation according to the channel
information corresponding to the sub-carriers to which the
inter-group transmission calibration pilot sequences are mapped
over each reference channel, to obtain channel information
corresponding to all the sub-carriers over each reference
channel.
[0319] In an implementation, the second determining unit 706 is
configured:
[0320] For each group of transmitting radio frequency channels,
[0321] To calculate a ratio of channel information obtained based
upon the inter-group transmission calibration pilot sequences, to
channel information based upon the intra-group transmission
calibration pilot sequences, of the reference channel of the group
of transmitting radio frequency channels as a revision coefficient
corresponding to the group of transmitting radio frequency
channels; and
[0322] To calculate a product of the revision coefficient
corresponding to the group of transmitting radio frequency
channels, and the channel information of each transmitting radio
frequency channel in the group of transmitting radio frequency
channels obtained based upon the intra-group transmission
calibration pilot sequences as revised channel information of each
transmitting radio frequency channel in the group of transmitting
radio frequency channels.
[0323] In an implementation, the second processing unit 705 is
configured:
[0324] To perform channel estimation on each group of transmitting
radio frequency channels according to the feedback signals of the
intra-group transmission calibration pilot sequences received over
the calibration receiving channel, to obtain channel information
corresponding to the sub-carriers to which the intra-group
transmission calibration pilot sequences are mapped over each group
of transmitting radio frequency channels; and
[0325] To perform interpolation according to the channel
information corresponding to the sub-carriers to which the
intra-group transmission calibration pilot sequences are mapped
over each group of transmitting radio frequency channels, to obtain
channel information corresponding to all the sub-carriers over each
group of transmitting radio frequency channels.
[0326] In an implementation, the first processing unit 702 is
configured:
[0327] To map the intra-group transmission calibration pilot
sequences corresponding respectively to the respective groups of
transmitting radio frequency channels onto the sub-carriers in the
entire operating bandwidth of the transmitting radio frequency
channels, where the spacing between the sub-carriers to which the
respective transmitting radio frequency channels are mapped is a
third sub-carrier offset which is more than or equal to the number
of channels in a group of transmitting radio frequency channels,
and the spacing between sub-carriers to which two adjacent
transmitting radio frequency channels are mapped is a fourth
sub-carrier offset which is less than the third sub-carrier
offset.
[0328] In an implementation, the transmission timeslots are guard
timeslots; and a first transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in a first group of transmitting radio frequency
channels, and a second transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in a second group of transmitting radio frequency
channels are two adjacent guard timeslots, or the first
transmission timeslot is spaced from the second transmission
timeslot by X guard timeslots, where the first group of
transmitting radio frequency channels, and the second group of
transmitting radio frequency channels are any two groups of
transmitting radio frequency channels with adjacent transmission
timeslots of their intra-group transmission calibration pilot
sequences, and X is an integer more than or equal to 1.
[0329] As can be apparent from the disclosure above, the
transmitting radio frequency channels in the array of antenna are
grouped into M groups, and the intra-group transmission calibration
pilot sequences of the corresponding groups are transmitted
respectively in the transmission timeslots corresponding
respectively to the respective groups of transmitting radio
frequency channels, where the transmission timeslots of the
intra-group transmission calibration pilot sequences corresponding
to the different groups are different from each other, that is, for
the M groups transmitting radio frequency channels, the intra-group
transmission calibration pilot sequences of the respective groups
of transmitting radio frequency channels are transmitted in the
different transmission timeslots in the time division mode, so
channel estimation can be performed separately on each group of
transmitting radio frequency channels, and if channel estimation is
performed on each group of transmitting radio frequency channels in
the frequency division mode, then simply the intra-group
transmission calibration pilot sequences will be transmitted over
different frequency resources in respective transmitting radio
frequency channels in a group, that is, for each group of
transmitting radio frequency channels, intra-group transmission
calibration pilot sequences corresponding to each group can be
mapped into the group of transmitting radio frequency channels in
the frequency division mode, so there are such a smaller number of
transmitting radio frequency channels in each group that longer
intra-group transmission calibration pilot sequences can be mapped
onto the respective radio frequency channels in the group in the
frequency division mode; and furthermore there is an increase in
the length of the intra-group transmission calibration pilot
sequences for channel estimation mapped onto the respective radio
frequency channels, the precision of the determined inter-channel
compensation coefficients of the respective transmitting radio
frequency channels can be improved.
[0330] FIG. 8 illustrates a schematic structural diagram of an
apparatus for calibrating an antenna.
[0331] Based upon the same idea, an embodiment of the invention
further provides an apparatus for calibrating an antenna as
illustrated in FIG. 7, which includes a transceiver 801, a
processor 802, and a memory 803, where:
[0332] The processor 802 is configured to read and execute program
in the memory 803:
[0333] To obtain information about grouping of transmitting radio
frequency channels, where the transmitting radio frequency channels
in an array of antennas are grouped into M groups, and M is an
integer more than 1;
[0334] To transmit intra-group transmission calibration pilot
sequences corresponding respectively to the respective groups of
transmitting radio frequency channels over the corresponding groups
of transmitting radio frequency channels respectively in
transmission timeslots of the intra-group transmission calibration
pilot sequences, and to perform channel estimation on the
respective groups of transmitting radio frequency channels
according to feedback signals of the intra-group transmission
calibration pilot sequences received over a calibration receiving
channel to obtain channel information of the M groups of
transmitting radio frequency channels, where there are different
transmission timeslots of intra-group transmission calibration
pilot sequences corresponding to different groups; and
[0335] To determine inter-channel compensation coefficients of the
respective transmitting radio frequency channels according to the
channel information of the M groups of transmitting radio frequency
channels.
[0336] The transceiver 801 can include a baseband processing
component, a radio frequency processing component, and other
components as needed in practice, and is configured to transmit the
intra-group transmission calibration pilot sequences over the
transmitting radio frequency channels in the respective groups, and
to receive the feedback signals of the intra-group transmission
calibration pilot sequences over the calibration receiving
channel.
[0337] In an implementation, each group of transmitting radio
frequency channels includes N transmitting radio frequency
channels, where N is 1, or N is an integer more than 1. If N is an
integer more than 1, then intra-group transmission calibration
pilot sequences will be transmitted over different frequency
resources in respective transmitting radio frequency channels in a
group.
[0338] In an implementation, the processor 802 is configured:
[0339] To select a reference channel from each group of
transmitting radio frequency channels respectively according to the
channel information of each group of transmitting radio frequency
channels to obtain M reference channels;
[0340] To transmit inter-group transmission calibration pilot
sequences over the M reference channels, and to perform channel
estimation on the M reference channels according to feedback
signals of the inter-group transmission calibration pilot sequences
received over the calibration receiving channel to obtain channel
information of the M reference channels; and
[0341] To revise the channel information of the group of
transmitting radio frequency channels corresponding to each
reference channel respectively according to the channel information
of each reference channel; and to determine the inter-channel
compensation coefficient of each transmitting radio frequency
channel according to the revised channel information of each group
of transmitting radio frequency channels.
[0342] In an implementation, the processor 802 is configured:
[0343] For each group of transmitting radio frequency channels,
[0344] To determine receive power of each transmitting radio
frequency channel in the group of transmitting radio frequency
channels; and
[0345] To determine transmitting radio frequency channels with
their receive power being not below a first threshold as active
transmitting radio frequency channels, and to select a reference
channel from all the active transmitting radio frequency channels
in the group of transmitting radio frequency channels according to
the receive power of all the active transmitting radio frequency
channels in the group of transmitting radio frequency channels.
[0346] The processor 802 is configured:
[0347] To map the inter-group transmission calibration pilot
sequences onto the sub-carriers in the entire operating bandwidth
of each reference channel, where the spacing between sub-carriers
to which each reference channel is mapped is a first sub-carrier
offset more than or equal to M, and the spacing between
sub-carriers to which two adjacent reference channels are mapped is
a second sub-carrier offset less than the first sub-carrier
offset.
[0348] In an implementation, the processor 802 is configured:
[0349] To transmit the inter-group transmission calibration pilot
sequences over the M reference channels in a transmission timeslot
of the inter-group transmission calibration pilot sequences in the
current calibration period, where the inter-group transmission
calibration pilot sequences are transmitted over different
frequency resources of the M reference channels.
[0350] In an implementation, the processor 802 is configured:
[0351] To perform channel estimation on the M reference channels
according to the feedback signals of the inter-group transmission
calibration pilot sequences received over the calibration receiving
channel, to obtain channel information corresponding to the
sub-carriers to which the inter-group transmission calibration
pilot sequences are mapped over each reference channel; and
[0352] To perform interpolation according to the channel
information corresponding to the sub-carriers to which the
inter-group transmission calibration pilot sequences are mapped
over each reference channel, to obtain channel information
corresponding to all the sub-carriers over each reference
channel.
[0353] In an implementation, the processor 802 is configured:
[0354] For each group of transmitting radio frequency channels,
[0355] To calculate a ratio of channel information obtained based
upon the inter-group transmission calibration pilot sequences, to
channel information based upon the intra-group transmission
calibration pilot sequences, of the reference channel of the group
of transmitting radio frequency channels as a revision coefficient
corresponding to the group of transmitting radio frequency
channels; and
[0356] To calculate a product of the revision coefficient
corresponding to the group of transmitting radio frequency
channels, and the channel information of each transmitting radio
frequency channel in the group of transmitting radio frequency
channels obtained based upon the intra-group transmission
calibration pilot sequences as revised channel information of each
transmitting radio frequency channel in the group of transmitting
radio frequency channels.
[0357] In an implementation, the processor 802 is configured:
[0358] To perform channel estimation on each group of transmitting
radio frequency channels according to the feedback signals of the
intra-group transmission calibration pilot sequences received over
the calibration receiving channel, to obtain channel information
corresponding to the sub-carriers to which the intra-group
transmission calibration pilot sequences are mapped over each group
of transmitting radio frequency channels; and
[0359] To perform interpolation according to the channel
information corresponding to the sub-carriers to which the
intra-group transmission calibration pilot sequences are mapped
over each group of transmitting radio frequency channels, to obtain
channel information corresponding to all the sub-carriers over each
group of transmitting radio frequency channels.
[0360] In an implementation, the processor 802 is configured:
[0361] To map the intra-group transmission calibration pilot
sequences corresponding respectively to the respective groups of
transmitting radio frequency channels onto the sub-carriers in the
entire operating bandwidth of the transmitting radio frequency
channels, where the spacing between the sub-carriers to which the
respective transmitting radio frequency channels are mapped is a
third sub-carrier offset which is more than or equal to the number
of channels in a group of transmitting radio frequency channels,
and the spacing between sub-carriers to which two adjacent
transmitting radio frequency channels are mapped is a fourth
sub-carrier offset which is less than the third sub-carrier
offset.
[0362] In an implementation, the transmission timeslots are guard
timeslots; and a first transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in a first group of transmitting radio frequency
channels, and a second transmission timeslot in which the
intra-group transmission calibration pilot sequences are
transmitted in a second group of transmitting radio frequency
channels are two adjacent guard timeslots, or the first
transmission timeslot is spaced from the second transmission
timeslot by X guard timeslots, where the first group of
transmitting radio frequency channels, and the second group of
transmitting radio frequency channels are any two groups of
transmitting radio frequency channels with adjacent transmission
timeslots of their intra-group transmission calibration pilot
sequences, and X is an integer more than or equal to 1.
[0363] Here in FIG. 8, the bus architecture can include any number
of interconnecting buses and bridges to particularly link together
various circuits including one or more processors represented by
the processor 802, and one or more memories represented by the
memory 803. The bus architecture can further link together various
other circuits, e.g., prophetical devices, manostats, power
management circuits, etc., all of which are well known in the art,
so a further description thereof will be omitted in this context.
The bus interface serves as an interface. The transceiver 801 can
be a number of elements including a transmitter and a receiver
which are units for communication with various other devices over a
transmission medium. The processor 802 is responsible for managing
the bus architecture and performing normal processes, and the
memory 803 can store data for use by the processor 802 in
performing the operations.
[0364] As can be apparent from the disclosure above, the
transmitting radio frequency channels in the array of antenna are
grouped into M groups, and the intra-group transmission calibration
pilot sequences of the corresponding groups are transmitted
respectively in the transmission timeslots corresponding
respectively to the respective groups of transmitting radio
frequency channels, where the transmission timeslots of the
intra-group transmission calibration pilot sequences corresponding
to the different groups are different from each other, that is, for
the M groups transmitting radio frequency channels, the intra-group
transmission calibration pilot sequences of the respective groups
of transmitting radio frequency channels are transmitted in the
different transmission timeslots in the time division mode, so
channel estimation can be performed separately on each group of
transmitting radio frequency channels, and if channel estimation is
performed on each group of transmitting radio frequency channels in
the frequency division mode, then simply the intra-group
transmission calibration pilot sequences will be transmitted over
different frequency resources in respective transmitting radio
frequency channels in a group, that is, for each group of
transmitting radio frequency channels, intra-group transmission
calibration pilot sequences corresponding to each group can be
mapped into the group of transmitting radio frequency channels in
the frequency division mode, so there are such a smaller number of
transmitting radio frequency channels in each group that longer
intra-group transmission calibration pilot sequences can be mapped
onto the respective radio frequency channels in the group in the
frequency division mode; and furthermore there is an increase in
the length of the intra-group transmission calibration pilot
sequences for channel estimation mapped onto the respective radio
frequency channels, the precision of the determined inter-channel
compensation coefficients of the respective transmitting radio
frequency channels can be improved.
[0365] Those skilled in the art shall appreciate that the
embodiments of the invention can be embodied as a method, a system
or a computer program product. Therefore the invention can be
embodied in the form of an all-hardware embodiment, an all-software
embodiment or an embodiment of software and hardware in
combination. Furthermore the invention can be embodied in the form
of a computer program product embodied in one or more computer
useable storage mediums (including but not limited to a disk
memory, a CD-ROM, an optical memory, etc.) in which computer
useable program codes are contained.
[0366] The invention has been described in a flow chart and/or a
block diagram of the method, the device (system) and the computer
program product according to the embodiments of the invention. It
shall be appreciated that respective flows and/or blocks in the
flow chart and/or the block diagram and combinations of the flows
and/or the blocks in the flow chart and/or the block diagram can be
embodied in computer program instructions. These computer program
instructions can be loaded onto a general-purpose computer, a
specific-purpose computer, an embedded processor or a processor of
another programmable data processing device to produce a machine so
that the instructions executed on the computer or the processor of
the other programmable data processing device create means for
performing the functions specified in the flow(s) of the flow chart
and/or the block(s) of the block diagram.
[0367] These computer program instructions can also be stored into
a computer readable memory capable of directing the computer or the
other programmable data processing device to operate in a specific
manner so that the instructions stored in the computer readable
memory create an article of manufacture including instruction means
which perform the functions specified in the flow(s) of the flow
chart and/or the block(s) of the block diagram.
[0368] These computer program instructions can also be loaded onto
the computer or the other programmable data processing device so
that a series of operational operations are performed on the
computer or the other programmable data processing device to create
a computer implemented process so that the instructions executed on
the computer or the other programmable device provide operations
for performing the functions specified in the flow(s) of the flow
chart and/or the block(s) of the block diagram.
[0369] Although the preferred embodiments of the invention have
been described, those skilled in the art benefiting from the
underlying inventive concept can make additional modifications and
variations to these embodiments. Therefore the appended claims are
intended to be construed as encompassing the preferred embodiments
and all the modifications and variations coming into the scope of
the invention.
[0370] Evidently those skilled in the art can make various
modifications and variations to the invention without departing
from the spirit and scope of the invention. Thus the invention is
also intended to encompass these modifications and variations
thereto so long as the modifications and variations come into the
scope of the claims appended to the invention and their
equivalents.
* * * * *